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  • From Pre-established Harmony to Physical Influx: Leibniz’s Reception in Eighteenth Century Germany

In the present essay I shall be concerned with the reception of Leibniz in Germany during approximately the first half of the eighteenth century. Since others (Barber 1955, Beck 1969, Saine 1987, Überweg 1894–1902, Wundt 1945, Wilson 1994, Zeller 1873) have already presented overviews of the reception of Leibniz’s philosophy as a whole during this period, 1 I [End Page 136] shall focus on how one of Leibniz’s most important and peculiar doctrines, namely Pre-established Harmony, was received in this period. In the first section I shall briefly present Leibniz’s views on Pre-established Harmony and explain how it was modified by Leibniz’s most important advocate in Germany, Christian Wolff. I shall also give some indication as to how Wolff’s philosophy in general and Pre-established Harmony in particular gained immediate acceptance (in the early 1720s). The second section will highlight some of the most important objections that the Pietists raised against Wolff’s version of Pre-established Harmony and Wolff’s defense against those objections (from circa 1723–27). The third section will consider how one main alternative to Pre-established Harmony, namely Physical Influx, emerged in a tentative way within the Wolffian school (from the mid 1720s to 1734). 2 In the fourth section I shall explain how Physical Influx was then developed not only to respond to Leibniz’s and the Pietists’s objections but also to allow for a more sophisticated positive explanation of physical influx (1735). 3 In the fifth section I shall describe how one last attempt was made (in the late 1730s and early 1740s) to rescue Pre-established Harmony by taking explicit recourse to Leibniz’s rather than Wolff’s position. In the sixth section I shall briefly indicate how, this last rescue attempt notwithstanding, Physical Influx established itself, albeit with important exceptions, as the standard view (in the 1740s and 1750s). Thus, I shall attempt to show how throughout the course of Leibniz’s reception in Germany during the first half of the eighteenth century a gradual shift occurred from Pre-established Harmony to Physical Influx.

I. Leibniz and Wolff on Pre-established Harmony

As a first approximation, Leibniz’s Pre-established Harmony 4 consists in the claims that no finite substance can act on any other finite substance 5 and that any changes that occur in a substance are due rather to that substance’s own causal efficacy; Pre-established Harmony implies both a denial of inter-substantial causation and an assertion of intra-substantial [End Page 137] causation. Accordingly, the main alternatives to Pre-established Harmony are Occasionalism, which denies all finite causation whatsoever (i.e., both inter- and intra-substantial causation amongst finite substances), and a view that Leibniz dubs “influxus physicus”, or Physical Influx, which asserts inter-substantial causation. 6 Since almost no German philosopher in this period accepts Occasionalism (despite the fact that it is discussed by virtually everyone interested in the debate), 7 it is possible to focus primarily on Physical Influx. Leibniz’s main objections to Physical Influx are twofold. First, it is inconceivable how one substance could act on another substance, given that it is absurd to hold that an accident could migrate from one substance to another. Second, Physical Influx violates the laws of nature, since if the mind could act on the body, then there would be more motion in the world after this act than before it, which contradicts the law of the conservation of motion as described by Descartes. 8

One of Leibniz’s important motivations for his assertion of intra-substantial causation is his account of substance. Leibniz defines a substance in terms of a complete concept, that is, a concept which contains within itself all that will ever be true of that substance. Accordingly, the changes that occur in a substance are merely the result of the unfolding of its complete concept, a process that occurs through the spontaneous activity of the basic force of appetition that each substance possesses. Since each substance contains all of its predicates within itself, there is no need for the causal activity of other substances (i.e., no need for inter-substantial causation). This explanation reveals why it is appropriate for Leibniz to use the term “pre-established”; all the predicates that will ever be true of a substance are ‘pre-determined’ or ‘pre-established’ in its complete concept. The “harmony” Leibniz describes arises because God has created substances that mirror each other completely in their internal changes. Accordingly, when I twist my hand in a certain way the doorknob turns, despite the fact that there is no causal interaction between my hand and the doorknob. Leibniz sometimes attempts to avoid the deterministic consequences that might seem to follow from his complete concept account of substance by distinguishing between the absolute necessity of God’s understanding and the hypothetical necessity of God’s will. Determinism is allegedly avoided because the possible world that God chooses to create is merely hypothetically necessary (i.e., necessary, given God’s [End Page 138] will), not absolutely necessary (that is, its denial would not imply a contradiction). 9

For Leibniz Pre-established Harmony is both a description of the general relationship between all finite substances and a solution to the specific problem posed by the mind-body relationship. However, the way in which Pre-established Harmony solves the mind-body problem is not as straightforward as one might think. The mind-body problem in its Cartesian form is that the mind and the body seem unable to act on each other due to the radical distinctness of their respective natures; the principal attribute of body is extension, whereas that of the mind is thought. Leibniz’s Pre-established Harmony might seem to solve the specific mind-body problem by agreeing that the mind and the body cannot act on each other on the general grounds that no two finite substances can act on each other, but at least sometimes Leibniz solves the problem by changing the metaphysical status of bodies. One of Leibniz’s motivations for this change stems from the following line of argumentation. Leibniz holds as a conceptual truth that the reality of a composite depends on the reality of its parts. Since bodies are composite, their reality must depend on the reality of their parts. But if the parts of bodies are extended and extension implies infinite divisibility, then bodies qua extended composites must depend for their existence on non-extended simples. 10 Thus, at least in his later period, Leibniz reduces bodies to well-founded phenomena insofar as they are grounded in the perceptions of metaphysical points or monads (which are simple substances endowed with a representative force). 11 In accord with this view, Leibniz solves the mind-body problem by eliminating bodies and then redescribing Pre-established Harmony as the consistency or agreement that exists between the realm of efficient causes (which holds for phenomenal bodies) and the realm of final causes (which holds for ultimately real monads). Many of Leibniz’s most important doctrines 12 such as the Principle of Identity, the Principle of Sufficient Reason, an ontology of simple beings (akin to Leibniz’s monads) endowed with [End Page 139] forces, 13 and Pre-established Harmony were adopted by Christian Wolff in his metaphysics textbook: Vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt (1719–20). While Wolff repeated several of Leibniz’s objections to Physical Influx and Occasionalism, he modified Leibniz’s positive explanation of Pre-established Harmony in several respects. 14 First, Wolff’s version of Pre-established Harmony is agnostic as to whether bodies have representational force. At §§125–26 of the Vernünfftige Gedancken Wolff argues that any simple element must have a basic force. From this 15 Wolff concludes that “the inner state of every simple thing is directed toward (‘richtet sich nach’) the others that lie around it. Thus, all are in concord with each other, so that the perfection in the composite is conserved” (Wolff [1719–20] 1983, p. 367, §595). 16 However, despite his apparent agreement with Leibniz about the general idea underlying Pre-established Harmony, Wolff, unlike Leibniz, is not ready to explain this directedness in terms of a representational force:

Since I have distinctly shown above that the inner state of every simple thing refers to all the other things that exist in the world (§596) and Herr von Leibniz explains this in such a way that the whole world is represented in each simple thing according to the point where it is (§599), thus one also understands further how everything in the world down to the smallest thing coheres with any other according to his opinion. What he advances with his general harmony of things, like all the other claims that he makes in this regard, appears to many as a puzzle that they believe to be unsolvable, since he has neither explained nor proved it sufficiently. However, because at the present time we do not want to decide what it really means for the inner state of simple things to refer to everything in the world, we shall let it remain undecided for the present in what the general harmony of things consists, and it is [End Page 140] enough for us that we show that it is present and that it can be explained in an intelligible manner according to the sense of Herr von Leibniz.

(Wolf [1719–20] 1983, pp. 370–71, §600)17

Although Wolff does not indicate in any positive way what the coherence or connectedness of the simple beings that constitute bodies amounts to, it is clear that he is distancing himself from Leibniz’s explanation of the ‘directedness’ of each monad in terms of a representational force. 18 However, from Wolff’s reluctance to attribute representational powers to all monads it follows neither that he is a dualist nor that he accepts causation between the simple beings that constitute bodies. 19

Second, although Pre-established Harmony is central to Leibniz’s system, 20 during the course of his career Wolff increasingly demotes it to the periphery of his philosophy. In the preface to his Vernünfftige Gedancken, 21 Wolff explains that initially he wanted to leave the question of [End Page 141] Pre-established Harmony open. However, when he comes to discuss the mind-body problem in the section on rational psychology, he finds that contrary to his initial expectations he has been led completely naturally to Pre-established Harmony by the principles adopted in earlier chapters. Accordingly, Wolff clearly accepts Pre-established Harmony, but only as a doctrine that follows from other, more central principles. Then, as time goes by, Wolff de-emphasizes the view, repeatedly suggesting that “not much rests on finding this system [i.e., Pre-established Harmony] more probable than the others” (Wolff [1724d] 1983, p. 487). 22 Thus, Wolff generally seems less committed to Pre-established Harmony than is Leibniz, though it is clearly his own preferred solution to the mind-body problem, and, as time goes on, he downplays Pre-established Harmony even more.

Third, Wolff repeatedly states that direct experience alone cannot decide the issue between Pre-established Harmony and Physical Influx. In other words, Wolff expressly acknowledges the Humean point (before Hume) that one cannot directly perceive causal interactions between substances. While Leibniz does not suggest that direct experience could be used to refute Physical Influx, he does not explicitly assert that something besides direct experience (e.g., the laws of motion, conceptions of substance) must allow us to decide the issue.

After the publication of his Vernünfftige Gedancken in 1719–1720, Wolff quickly found widespread support. Wolff’s clear and engaging teaching style made him popular amongst his students. 23 The fact that Wolff wrote in German clearly contributed to his success both in academics and in the wider reading public that was emerging at the time. Wolff’s systematic exposition of a large portion of Leibniz’s doctrines fulfilled an important function in the popularization of philosophy in general and Leibniz’s philosophy in particular. 24 Also, more generally, Wolff’s philosophy was quite sympathetic to the social, political, and economic forces that combined to form the core of the German Enlightenment. Finally, Wolff’s students both occupied important positions in universities and published widely, thus further popularizing the Leibnizian-Wolffian philosophy. [End Page 142]

Two of Wolff’s students who are important for Pre-established Harmony were Ludwig Philipp Thümmig (1697–1728), professor of philosophy in Halle, and Georg Bernhard Bilfinger (1693–1750), professor of philosophy first in St. Petersburg, then in Tübingen. 25 In 1725–26 Thümmig published his own textbook, Institutiones philosophiae Wolfianae, which is primarily a repetition of Wolff’s doctrines. Thümmig’s textbook is substantially shorter and less detailed than Wolff’s, however, covering Wolff’s entire theoretical and practical philosophy in only two volumes. 26 On the issue of the commerce of the mind and the body, Thümmig presents all three causal theories (as well as some of the arguments for and against each theory) and seems to give priority to Pre-established Harmony. For “the systems of physical influx and assistance [occasionalism] are contrary to the order of nature . . . and the system of pre-established harmony alone conforms to it because something is not to be used for explaining the commerce between the mind and the body unless the essence and nature of the mind and body agrees with it” (Thümmig [1725] 1982, p. 195). 27 However, at the end of this section Thümmig does weaken his adherence to Pre-established Harmony somewhat. He notes first that none of these three theories has any implications for practical issues (e.g., ethics, religion), and then that “because none of these systems has been advanced with a rigorous demonstration, it will be the same to us, whether someone wishes, as this or another system comes to appear probable, to accept the position of the influxionists, or the occasionalists or finally the harmonists, or to defend none at all” (Thümmig [1725] 1982, p. 197). 28 Thus, while Thümmig himself is a faithful Wolffian on the issue, he seems to be willing to allow for rational disagreement.

Of more immediate relevance on the issue of Pre-established Harmony is Bilfinger, for in 1723 he published a revised version of his dissertation from 1721 under the title De Harmonia animi et corporis humani maxime praestabilita ex mente illustris Leibnitii, commentatio hypothetica, a treatise [End Page 143] expressly devoted to defending Pre-established Harmony. 29 Further, Bilfinger, unlike Thümmig, established his independence from Wolff by considering and citing Leibniz’s position and not only or primarily Wolff’s. The first and second sections of this treatise give a general introduction to the various causal systems. Two points are especially worthy of note. First, Bilfinger explicitly argues that there can be only three possible causal theories, namely Physical Influx, Occasionalism, and Pre-established Harmony. Second, whereas Wolff seemed to endorse Pre-established Harmony in an unspecified way for non-mind-body relations, Bilfinger is clear in his assertion that Pre-established Harmony does not hold for the relationship between bodies. 30 The third and fourth sections discuss Physical Influx and Occasionalism, respectively. Bilfinger rejects Physical Influx for many of the standard reasons (it seems to violate the law of the conservation of motion and it draws too great a distinction between the mind and the body), but he also adds several of his own objections. For example, he objects that Physical Influx can be known neither a priori nor a posteriori, and it must therefore be false (Bilfinger [1723] 1984, p. 27). He also objects on metaphysical rather than physical grounds that the whole effect must be equal to (and not greater than) the full cause, but according to Physical Influx the whole effect is greater than the full cause, because one motion can cause another equal motion in a collision (which should exhaust its effect) plus an idea in the mind (which, the objection goes, amounts to more than what the initial cause contained) (Bilfinger [1723] 1984, pp. 37–44). Similarly, Physical Influx is to be rejected because there could be no proportion (since no homogeneity) between the mind and the body (Bilfinger [1723] 1984, p. 53). The fifth and sixth sections explain and defend Pre-established Harmony against several objections raised by Foucher, Bayle, Lamy, Tournemine, Newton, Clarke, and Stahl.

In the final section Bilfinger sets out systematically the advantages Pre-established Harmony enjoys. First, it coheres with religion because Pre-established Harmony emphasizes God’s perfections (e.g., necessary existence, free agency, providence, power, and knowledge). Second, it is also well-suited to the nature of human beings because its denial of inter-substantial causation underscores the independence of human beings from other creatures, while its assertion of intra-substantial causation highlights both the perfect spontaneity and the immortality of the soul. While [End Page 144] Bilfinger did not adduce any new arguments for Pre-established Harmony, his clear, systematic, and thorough defense of Pre-established Harmony with respect to the mind-body issue had considerable influence, since many took his view to be the definitive statement of Pre-established Harmony. 31

Accordingly, in the early 1720s Wolff popularizes many of Leibniz’s doctrines, and his followers contribute to the popularity of Wolff and Leibniz by disseminating Leibnizian-Wolffian doctrines (Thümmig), adducing for reasons in support of Pre-established Harmony (Bilfinger) and at times suggesting minor alterations to Leibniz’s view (Wolff and Bilfinger).

II. The Pietistic Attack and the Wolffian Defense

A. The Intellectual Background

While Wolff certainly enjoyed considerable success and popularity in many circles, he was not without opposition. For instance, at the university in Halle (and especially in its theological faculty) a number of Pietists were opposed to the Enlightenment in general and Wolff’s philosophy in particular. Twenty years before, Christian Thomasius (one of the prominent leaders of the university and, at least initially, one not only sympathetic to the Pietist movement but also partly responsible for its dominance at the university) was censured for his criticism of the educational institutions (Waisenhäuser) that one of the leading Pietist figures, August Hermann Francke, had established according to Pietist ideals. Thus, in 1702 a royal decree prohibited Thomasius from lecturing on any topic other than law. In 1714, one of Francke’s followers, Joachim Lange, along with other members of the theology faculty at Halle, even attempted to have further restrictions placed on Thomasius. While this attempt was not completely successful (in part, ironically, because of Francke himself), Thomasius’s situation was less than ideal. 32 Wolff was, if anything, even more suspect to the Pietists. In 1717 the Pietists secretly sent students to his lectures to determine whether anything he said was hostile to pietism and if so, what could be used to make a case against him. Although the material they gathered was apparently not enough to force Wolff to alter his lectures, he was called in to meet with Francke and had to make some [End Page 145] kind of apology. Thus, the atmosphere at the university in Halle was not quite as comfortable for Wolff as one might have expected, given the widespread acclaim and acceptance he received in many circles.

After 1720 the situation in Halle deteriorated rather quickly for Wolff. On 12 July 1721 Wolff’s duties as vice-chancellor came to an end, and, as was standard procedure for such an occasion, Wolff gave a ceremonial address in order to celebrate the passing of the torch to his successor. But Wolff did not give just any address; he gave a speech entitled Oratio de Sinarum philosophia practica on the practical philosophy of the Chinese. The point of this speech was far from arbitrary. He argued that Confucius’s practical philosophy was essentially based on reason alone and was thus worthy of praise and admiration. This was an affront to the Pietists and must have outraged them. 33 Since they insisted on a person’s individual supra-rational relation to God and the impotence of reason concerning any matters of spiritual weight, they could only interpret Wolff’s address as an attack on their position. Further, the speech was not timed to please, inasmuch as the person who was to take over the vice-chancellorship from Wolff was none other than the head of the theology faculty, Joachim Lange. Lange, presumably furious about the content of the speech, demanded the right to censor Wolff’s talk before its publication. Wolff refused on the grounds that the theology faculty had no authority over the philosophy faculty and it was not competent to judge a philosophical work. 34 Needless to say, Wolff’s behavior did not improve a situation that was already precarious. 35

At this point, the sides had been drawn, and the fight was on between the Pietists and Wolffians. The Pietists were primarily theologically motivated and educated, whereas the proponents of the Enlightenment were philosophically interested and trained. In March 1723, one of Lange’s supporters, Daniel Strähler, published his Prüfung der Vernünftigen Gedanken Wolffs von Gott, der Welt, usw., which critically scrutinizes the first three chapters of Wolff’s Vernünfftige Gedancken. His plan to do the same for the rest of Wolff’s Vernünfftige Gedancken was halted only due to a royal [End Page 146] rescript. 36 Wolff responded to Strähler’s work in the very same month with his Sicheres Mittel. 37 In July 1723, Lange himself entered the fray with his Anmerckungen über des Herrn Hoff-Raths und Professor Christian Wolffens Metaphysicam 38 (hereafter: Anmerckungen), signed by the Theological Faculty in Halle. Wolff replied to this work with his Gründliche Antwort, which was published along with Lange’s Anmerckungen in 1724. Lange then wrote the first edition of his Causa Dei et religionis naturalis adversus atheismus, to which Wolff replied in August of 1723 with De differentia nexus rerum. 39 In the fall of 1723 Lange published his Modesta disquisitio, 40 to which Wolff responded in October 1723 with Monitum. 41 In November (still 1723) Lange replied to Wolff’s replies with Placidae vindiciae. 42

On 8 November 1723 a decisive blow was struck. Apparently, members of King Frederick William I’s “tobacco cabinet” (allegedly a group of military cronies with whom the king liked to smoke cigars) told him that according to Wolff’s Pre-established Harmony, a deserter from the army could not be held responsible for his action (given that it was “pre-established”), an idea for which the king clearly had no sympathy. 43 Accordingly, the king removed Wolff from his professorship at Halle and ordered him to leave Prussia within 48 hours or be executed. 44 Wolff was able to accept an offer at the university in Marburg, where he stayed until 1740, when he returned to Halle upon the repeated invitation of “the philosopher king,” Frederick the Great. (It is worth noting that at least in part due to his understandable mistrust of being so close to the king, Wolff [End Page 147] declined Frederick the Great’s offer to direct the Prussian Academy of Sciences at Berlin along with Maupertuis.) In short, Wolff was expelled due to his adherence to Pre-established Harmony!

Even with Wolff away in Marburg, the debate did not cease. For in 1723 Johann Franz Budde (1667–1729), 45 professor of theology in Jena and another leading Pietist figure, was asked by the Theology Faculty in Jena to write a report on Wolff’s views. This report, quite hostile to Wolff, was then published without Budde’s permission (indeed, without his knowledge) as Bedencken über die Wolffianische Philosophie. 46 Wolff replied to Budde’s work in February 1724 with Anmerkungen über das Buddeischen Bedenken von der Wolffischen Philosophie. 47 Since Budde was not an entirely voluntary party in the dispute, and the assumption seemed to be that whoever published the last word would be victorious in the debate, Johann Georg Walch (1693–1775), a close colleague of Budde in Jena, published an anonymous reply in 1724 to Wolff’s Anmerkungen entitled Bescheidene Antwort. 48 In August Wolff replied in turn with his Nöthige Zugabe. 49 (Wolff also published his lengthy Anmerkungen zur Deutschen Metaphysik 50 in 1724.) In 1725, Walch replied to Wolff’s Nöthige Zugabe, once again anonymously, with his Bescheidener Beweiß, 51 and in September Wolff indefatigably replied in turn with his Klarer Beweis. 52 Although this work marked the end of any direct exchange between Wolff and the Pietists, [End Page 148] both sides continued to publish their viewpoints. In 1725 Lange published his Ausführliche Recension and in 1726 Nova Anatome, while Wolff published his Ausführliche Nachricht. 53 What is particularly striking about the mere form of this debate is not only the rapidity with which attack and counterattack proceeded, but also the fact that most of these works were between two hundred and five hundred pages.

It is also worth noting that the debate was not limited to Wolff and the Pietist opponents mentioned above. The intellectual pastime of aspiring young philosophers was to compose at times lengthy diatribes against the opposing position. 54 Hartmann, who had already written a history of the Leibnizian-Wolffian philosophy in 1737, notes: “Just as in the past year Wolff’s metaphysics was hotly contested; it continues with the same intensity in this year 1725 which one can see sufficiently from published works which are now listed in the following” (Hartmann [1737] 1973, p. 899). 55 Hartmann proceeds to cite twelve other attacks on Wolff published in 1725; this list does not even include those works supporting Wolff. 1726 is no different. As Hartmann notes: “Nor in the year of 1726 did one cease or even slow down refuting Wolff’s philosophy, as we can see from the following works” (Hartmann [1737] 1973, p. 906). 56 Again, a sizable list of only those works that attack Wolff is enumerated. The last major Pietist figure who engages in a direct philosophical debate with Wolff (though the term ‘debate’ is to be understood more loosely here, since Wolff does [End Page 149] not respond) is Andreas Rüdiger, who published his Gegenmeinung in 1727. 57 Otherwise, as Hartmann notes: “Now it began to become somewhat quieter in this year. For although Lange’s party grew and increased daily through various recruits, and the older members continued the disputes they had started, they still felt now a great shortage of sufficient ammunition” (Hartmann [1737] 1973, p. 928). 58

B. The Philosophical Relevance of the Debate: Lange’s Objections

What is the philosophical content of the Pietists’ diatribe against Leibniz and Wolff? And do Wolff’s replies deepen our understanding of the possibilities inherent in a Leibnizian position? In the rest of this section I discuss the philosophical high points of Wolff’s debate with Strähler, Lange, Budde, Walch, and Rüdiger, especially insofar as they give a sense of what these Pietists considered important about Leibniz’s and Wolff’s positions. Strähler’s discussion is rather disappointing because his criticisms take the form of a petty point-by-point commentary on Wolff’s Vernünfftige Gedancken. However, Lange’s critique is somewhat more important. While the majority of his remarks are primarily intentional misrepresentations of Wolff’s position, baseless accusations, or personal attacks, the general thrust of Lange’s myriad criticisms is to accuse Wolff (and indirectly Leibniz) of determinism, fatalism, atheism, and Spinozism. 59 Further, these various charges allegedly follow from a surprisingly large number of Wolff’s doctrines (e.g., his accounts of possibility, contingency, necessity, miracles, and the divine understanding; his definitions of God, the world, and the soul; his denial of any beginning to the world; the laws of motion, etc.). While many of these criticisms are based on crude misunderstandings, it would be wrong to suggest that Lange has no [End Page 150] coherent position or that all of his criticisms obviously miss their mark. 60 For example, Lange suggests the following difficulty with Wolff’s account of miracles. On the Wolffian account of the connection of all things, if a miracle occurs in one thing the states of all others must be changed appropriately, and not just current events, but all events in the future, unless a “restitution miracle” also occurs, that is, a miracle that puts everything else back in its proper place (Wolff [1719–20] 1983, p. 389). 61 Lange finds this explanation of miracles, restitution miracles in particular, problematic because i) we do not read about restitution miracles in the Bible, and ii) it is not clear when such restitution miracles could occur (neither at the same time as the ‘original’ miracle occurs nor afterwards). Wolff’s account is misleading in that it may suggest that when God performs a miracle, God must change the complete concept of the things to which the miracles happen. But, according to Wolff’s own position, it is impossible for God to change the complete concepts of things, since they lie in God’s understanding and are distinct from what the divine will can bring about. 62 How does Wolff respond in his Gründliche Antwort? The remarkable feature of Wolff’s replies, here as elsewhere, is his ability to add no substantive content, despite devoting considerable space to each point that Lange raises. 63 Thus, in this instance Wolff merely repeats his original point that if a miracle occurs, it will have certain consequences that would not have occurred otherwise, and then he reassures the reader that nothing he is claiming here is dangerous. [End Page 151]

To get a sense of the ways in which Lange criticizes Wolff, consider briefly six of his criticisms that pertain to rational psychology. After first attacking Wolff’s generic definition of spirit (§1) (it is allegedly unclear, it inappropriately defines the spirit in terms of the corporeal world, and it does not distinguish God sufficiently), Lange’s second criticism (§2) impugns Wolff’s specific definition of the human soul on four counts. First, the essence of the soul is placed in its smallest power, namely that of representation. Second, since this force is not both active and passive, there is, in addition to liberty, no purely active faculty in the soul. Third, Wolff’s definition focuses on the world rather than God, who is, according to Lange, the soul’s true object. Fourth, Lange claims that Wolff’s definition of the soul precludes its immortality, since it makes explicit reference to the position of the body. After ignoring Lange’s first criticism, Wolff responds to the first two counts in his Gründliche Antwort by noting that the power of representation is an active principle and it is preferable for freedom to arise from an active rather than a passive principle (which is what Wolff implicitly attributes to Lange). In response to the third count, Wolff notes that a definition need not explain every property true of a substance, and thus he implicitly asserts that it is not problematic to mention only the soul’s representative force in its definition. In response to the fourth count, Wolff replies that precisely due to Pre-established Harmony the human soul need not depend on the body, since it acts without the action of the body. Far from precluding immortality, Pre-established Harmony accounts for its possibility.

Lange’s third criticism (§3) attributes a twofold mistake to Wolff: i) the soul is, for Wolff, without real freedom, and ii) the soul would proceed as it does now even if the world did not exist. Wolff’s response to the first point is that the soul lacks freedom with respect to sensations, but not necessarily with respect to other representations. To the second point he replies that this is not so much a mistake as a statement of what follows immediately from Pre-established Harmony. Lange’s fourth criticism (§4) claims that Wolff is committed to fatalism because he holds (Wolff [1719–20] 1983, pp. 464–65) that the soul can have only one force, namely that of representation, which Lange interprets as excluding the will and thus freedom. Wolff explains on the contrary that the soul, through its representative force, can perform a variety of different actions that pertain to either the understanding or the will, just as a candle, through its corporeal nature, can bring about a number of different effects (heat, light, texture, etc.). 64 In his fifth and sixth criticisms (§§5–6) Lange raises an important [End Page 152] philosophical issue that is repeatedly discussed in the dispute—the possibility of imputing actions to the soul according to Pre-established Harmony. Lange claims that the soul does not really have a (free) will if it has no control over the body’s actions, as Pre-established Harmony claims. Lange’s point is, in a way, perfectly understandable. How can we say that a will is being exercised if it does not have any causal effect on the body? And why should we attribute the action of a particular body (e.g., the mouth uttering words) to a soul that does not have causal control over it? Unfortunately, Wolff does not provide any satisfactory answers to these questions in his Gründliche Antwort (or elsewhere).

In the course of the ensuing debate between Wolff and Lange another philosophically important issue arises concerning the union of the mind and the body. In his Modesta Disquisitio Lange argues that Wolff denies the physical union between the soul and the body and asserts merely a metaphysical union between the two. Although Lange had already made this objection in the first edition of the Causa Dei, here he is much more explicit about what he means by a metaphysical union and exactly what difficulties it presents for the soul-body relationship as described according to Pre-established Harmony. Lange first notes that with respect to the soul-body relationship Wolff virtually abstains from using the term union. Lange then claims (with a citation from Leibniz in support) that a metaphysical union is one that consists merely in the harmony of two distinct things. The idea underlying this criticism is that according to Wolff’s account even two clocks that act in harmony would be a metaphysical union, but surely a person must be more than a metaphysical union, since two clocks should not qualify as a single person (given that they are two substances). In his Bescheidene und ausführliche Entdeckung der falschen und schädlichen Philosophie in dem Wolffianischen Systemate Metaphysico von Gott, der Welt und dem Menschen from 1724 Lange uses a more sensational example to make his point:

If the union between the body and the soul is not physical, or natural, but rather only metaphysical, and consists in a correspondence of actions, then a philosopher of this system can be in Europe with respect to his body, in particular in Germany at Halle, but be in Africa amongst the Hottentots with respect to the soul; and with such a correspondence of actions that if the soul in Africa thinks that the body moves in such and such a way, then the body in [End Page 153] Europe moves due merely to its structure and the surrounding bodies.

(Lange 1724b, p. 128)65

This objection is reminiscent of Tournemine’s remark in 1703 66 that Leibniz’s Pre-established Harmony does not explain the union of the mind and the body. Unfortunately, Wolff does not provide an informative reply.

C. The Philosophical Relevance of the Debate: Budde and Walch

Budde’s and Walch’s criticisms are much like Lange’s. Both lodge general accusations that Wolff is a Spinozist and an atheist, and that he denies freedom. Both Budde and Walch also seem to misrepresent Wolff’s position intentionally and to level personal attacks against him. Nonetheless, sometimes they raise important issues. In his Bedencken, Budde lodges three main criticisms of Pre-established Harmony. First, Budde, like Lange, objects to Wolff’s account of the imputability of actions on the grounds that if there is no causal connection between the soul and the body, then one cannot impute to the soul actions performed by the body. And as Budde notes, this issue has practical import, since the greatest sins are performed by the body, and if the actions of the body cannot be imputed to the soul, then the soul does not sin and cannot be punished. Wolff’s reply is somewhat unfortunate. On the one hand, Wolff makes the obvious point that one imputes actions to the soul, not to the body. On the other hand, Wolff denies that he asserts that the motions would proceed in the body even if the soul did not freely desire them. 67 As in his dispute with Lange, Wolff does not use Budde’s criticism as an opportunity to clarify his account of the conditions for imputing actions. Rather, Wolff baldly asserts that no difference arises between Pre-established Harmony and Physical Influx with respect to the imputability of actions (Wolff [1719–20] 1983, pp. 80–81). However, Budde’s original point, at least implicitly, is that Physical Influx can maintain that a causal tie between the soul and the body be a necessary condition for the imputation of an action, whereas Pre-established Harmony cannot. Thus, contra Wolff, there could very well be differences between Physical Influx and Pre-established [End Page 154] Harmony on this issue. Second, Budde criticizes Wolff’s definition of the soul as a being that represents the world to itself, because this allegedly robs the soul of its activity and thus of its freedom. Wolff responds to this charge by turning the objection against Physical Influx: since according to Physical Influx the body is causally active and the soul passive (at least with respect to sensations), the soul is robbed of its activity and thus of its freedom, whereas on his view the soul is necessarily active. Third, Budde raises the standard objection that Wolff can explain, e.g., the simultaneity of the changes in the soul and the changes in the body only by means of an absolute necessity. 68

While Walch, who continues the battle with Wolff on Budde’s behalf, levels mainly familiar charges, he does raise some new points. For example, Walch (§7) makes the standard accusation that Wolff’s system is necessitarian. However, he treats Wolff’s distinction between hypothetical and absolute necessity in a novel way. Instead of simply rejecting the distinction (as Strähler does) or raising theological issues (as Lange does), he argues that the distinction still does not save the freedom of human beings. For while the distinction does allow God to be free when creating the world from without, the necessary connection within the world does not allow for the freedom of human beings. In the second chapter of his Klarer Beweis, Wolff seems to argue in response that even if he did maintain an absolute necessity in the world, this fact would not harm our freedom. He notes that freedom would not be removed

even if it were true that this world necessarily had to exist and it were impossible that another could exist. For the fact that God would necessarily have had to bring forth this world rather than all others and would not have had any freedom in his choice would not change anything in its constitution. The world remains the same in the one case as in the other, whether I posit that God chose it freely or necessarily. The choice does not change anything.

Wolff’s explanation here might seem to be highly significant, because if it is to be taken seriously, it renders Budde’s attack on and Wolff’s use of the distinction between hypothetical and absolute necessity irrelevant for the purposes of Pre-established Harmony. There is some reason, however, not to attribute too much weight to this account. First, Wolff does clearly use the counterfactual mood in explaining this point, which indicates that he might not actually endorse this position. Second, it might be inconsistent with his explanation of freedom, since if the world is absolutely necessary, then the soul could not have chosen otherwise. 70 Third, later in the Klarer Beweis Wolff himself claims that “without the contingency of the world in the system of pre-established harmony, freedom cannot endure” (Wolff [1725] 1980, §68, p. 216). 71 Thus, it is best to read Wolff’s explanation with caution.

Walch also discusses (in §15) Wolff’s account of imputability. He notes that Wolff’s response to the initial charge is inadequate because Wolff cannot claim that the soul gives its consent to the body’s actions in any meaningful sense. He distinguishes between internal decisions which can be imputed to the soul, and bodily actions, which cannot be imputed to the soul according to (his interpretation of) Pre-established Harmony, illustrating this distinction through the difference between contemplated murder and “successful” murder. Wolff’s Pre-established Harmony can, he charges, give no satisfactory account of this distinction, since in both cases the soul’s action is the same. Unfortunately, Wolff’s reply does not significantly clarify the issue.

It is also worth noting here that despite his lengthy accusations, Walch, like both Lange and Budde, displays no apparent interest in developing his own causal theory (Physical Influx) in any positive way. Consider, for example, Walch’s way of dealing with Leibniz’s and Wolff’s objection that physical influx is inconceivable (given the absurdity of thinking that an accident would migrate from one substance to another). In §24 of his Bescheidener Beweis, Walch simply remarks that there are many things that we accept without understanding how they work.

D. The Philosophical Relevance of the Debate: Rüdiger

The final figure who plays an important role in the early debate between the Pietists and Wolff is Andreas Rüdiger (1673–1731). Rüdiger was educated as a medical doctor, but due to illness was often unable to [End Page 156] practice medicine. His philosophical development was influenced by Thomasius, and found expression both in university lectures and academic treatises, in particular, his systematic metaphysics, Philosophia synthetica (1706–7). It is also worth noting that Rüdiger’s interests in medicine and the natural sciences distinguished him from the other, more theologically oriented Pietists. Upon the urging of his readers and students, in 1727 he published his commentary on Wolff’s chapter on rational psychology in Rüdiger’s Gegenmeinung. 72

Rüdiger’s Gegenmeinung consists in a lengthy preface, a reprint of Wolff’s chapter on rational psychology, and Rüdiger’s own comments as footnotes to Wolff’s text. 73 The preface presents a systematic outline of his own philosophical position which he then uses as a basis to attack Wolff. Accordingly, a brief account of his unusual position as he stated it in the preface will be useful. First, Rüdiger claims that (§2) many of the difficulties that arise for the mind-body relationship stem from misunderstanding the nature of the body. Rüdiger objects to the standard characterization of the body as extension, asserting instead (§11) that the essence of body consists in elasticity. Rüdiger notes that if one adheres to the standard dualistic metaphysics, then the body consists in extension, the soul is characterized as non-extended, and “not only can one not understand how the body and soul act on each other, but one understands that it is impossible that they act on each other” (Rüdiger 1727, §12). 74 Rüdiger reports that Descartes and Leibniz attempted to solve the problem created by dualism by advancing Occasionalism and Pre-established Harmony, but they attacked the symptom rather than the cause. Accordingly, Rüdiger suggests that with a corrected understanding of body, soul, and matter, the difficulties that arise in understanding the mutual influence of the body and the soul dissolve (§13). 75 In the course of the preface’s Four Theorems, [End Page 157] Rüdiger develops a positive account of the body and the soul which makes it clear how these problems are to be solved.

Theorem I asserts that the general description of the body as an extended substance is false. His motivation for this point is interesting. Rather than making the general claim, as was typical at the time, that the soul and the body cannot act on each other because they are too distinct or too different (the one being material and the other being immaterial), he states the objection in the following, more specific way: since the soul is not extended and is thus not at a point, but all contact is at a point, it cannot touch or be in contact with the body (and vice versa). However, because he accepts as a postulate that “no action can occur in another without contact,” the soul and body cannot act on each other (Rüdiger 1727, §16). 76 Since Rüdiger does not want to accept the denial of the soul’s action on the body, he must redefine extension.

In Theorem II Rüdiger states that the terms ‘extension’ and ‘creation’ are synonymous. His argument for this Theorem is the following (§21):

For if there were a created substance that was not extended (extensa), then it would not have parts outside parts (partes extra partes): if it did not have parts outside parts (partes extra partes), then it would have no front and back parts; if it had no front and back parts, then it would have no beginning and no end, and still would not be God. Thus, one could not conceive of a created being, and if one could not conceive it, it would then be either nothing or it would belong to the unknown (ad incognitum). Thus, the non-extended (non-extensum) is taken either negatively in which case it means nothing or positively in which case it means something about which we know nothing. (Rüdiger 1727, §21)77

This explanation allows Rüdiger to infer that the soul is extended (and thus at a place so that it can act on a body), but this admission does not [End Page 158] make him a materialist, since extension is equivalent to creation, not, e.g., spatiality or infinite divisibility. 78

Theorem III asserts that the essence of body does not consist in extension. Given Theorem II, the argument is obvious. Since extension covers both the soul and the body, extension cannot express the essence of the body but is rather a genus for both the body and the soul. Theorem IV (§23) then states:

The whole parts (Partes integrantes) are not true parts (verae partes), but rather essential ones (Essentiales) and those other than organic (Organicae) and mechanical (Mechanicae). §23. For those are not true parts in natural things (verae partes in rebus naturalibus) that do not have the limits of their extension from God or nature, namely their inherent force; but the whole parts have the limits of their extension from the choice (arbitrio) of human beings: which is clear because according to how human beings desire, one whole part (pars integrans) is one hundred thousand times greater and one hundred thousand times smaller without God or nature contributing anything to this limitation: accordingly, the whole part is a human artifact and not an artifact of God and of nature. Conversely, the essential parts, as the elements, and the spirit have not only their force but also the limits of their extension from God and when they increase or decrease, this happens through the motive force that God gave them, that is through their nature, such that the mentioned limits are always a deed of God or of nature and do not depend on any choice of human beings.

(Rüdiger 1727, Theorem IV and §23)79

Rüdiger then applies these partes integrantes to the soul-body issue as follows: [End Page 159]

Thus when one says the soul, namely its subject, is material, and thus allows that whole parts can be attributed to its substance, it does not follow that it is a composite being, but rather only that it is a being created by God that cannot perish other than through the will and omniscience of the one who created it. Conversely, it would be a truly composite being, and one that also due to its internal constitution could perish, if one were to say that it were to consist in essential parts, e.g., in the elements. (Rüdiger 1727, §24) 80

Rüdiger then infers:

Thus I consider the subject (subjectum) of the soul to be material, but the soul itself, insofar as it is taken to be the form of the body (pro forma corporis), I consider along with other philosophers (philosophis) and theologians (theologis) to be immaterial (pro immateriali). However, the subject of the soul is not for that reason to be considered composite (pro compositio), but rather is and remains a most simple substance (substantia simplicissima), because the whole parts through which it must be conceived are not true but rather only imagined parts. (Rüdiger 1727, §26)81

Nor is the soul to be considered a body, because the essence of body does not consist in extension but rather elasticity. He notes “the soul itself, that is, considered abstractly, is immaterialis because it is something divine” (Rüdiger 1727, §27). 82 Accordingly, Rüdiger rejects Wolff’s concept of the soul. His justification for this lies in “a distinction between the subject and the force of the subject” (Rüdiger 1727, §28). 83 Thus, one will find

(1) that an immaterial subject cannot in any way and manner be understood, whereas an immaterial force can be understood to some [End Page 160] extent. Namely, a force means a faculty of motion; now even if one cannot conceive of the said faculty, one can certainly conceive of the motion . . . It is completely different with the subject. For by its very nature it is an extended being and has as such no form of motion: for this reason if one cannot conceive of extension in its case, there is nothing else left for one to conceive or understand.

(Rüdiger 1727, §28)84

Given this account of the nature of body and soul, Rüdiger then discusses Wolff’s rational psychology, Leibniz’s objections to Physical Influx, and his objections to Pre-established Harmony. First, Rüdiger criticizes Wolff’s definition of consciousness. Wolff describes consciousness as occurring when we distinguish things from each other (Wolff [1719–20] 1983, pp. 454–55). Rüdiger criticizes this definition because he asserts that one cannot define something through its effects (Rüdiger 1727, c, p. 4), and he also raises qualia as a possible counterexample to Wolff’s definition (Rüdiger 1727, c, pp. 5–6). Second, Rüdiger criticizes Wolff’s (and Leibniz’s) account of simples. He argues as follows: “For each true thing is either a substance or an accident. The author’s simple beings cannot be accidents, because they are supposed to have forces (§115). Thus they must be subjects or substances, but they cannot be substances either, because all substances without shape and size cannot, I do not want to say be, but cannot even be conceived” (Rüdiger 1727, e2, pp. 25–26). 85 Third, Rüdiger criticizes Wolff’s attribution of a force (Kraft) to the soul. He argues:

Since the soul is a simple being, §742, and a simple thing or being has no internal motion, §81, I do not understand how the soul has a force. For assume that a force is an effort at an internal motion. However, such an effort or force is useless if it does not attain its actuality, because God and nature do nothing in vain, thus there is an actual internal motion, at least for a while, in the soul, which the [End Page 161] author expressly denies of the simple things, or monads §.81.

(Rüdiger 1727, f2, pp. 26–27)86

It is thus not surprising when Rüdiger proceeds to criticize Wolff’s argument for the single faculty thesis. Rüdiger asserts, “One distinguishes distinct forces only from opposite or contrary ones. The example that the author gives is for contrary forces and does not prove anything for him, because he wants to show only that a simple thing cannot have different forces” (Rüdiger 1727, g2, pp. 27–28). 87 Rüdiger also accepts the standard objection to Wolff’s claim that he can deduce all other faculties from the faculty of representation (Rüdiger 1727, r2, pp. 37–40). 88 However, his grounds are novel: one cannot deduce unknown (physical) effects (e.g., the motion of the body) from a metaphysical cause. It is also worth noting in this context that in addition to his more metaphysically oriented objections Rüdiger also accepts the traditional Pietist objections to Pre-established Harmony. He writes: “For I freely say that I am of the same opinion as others who have resisted the hypothesis of pre-established harmony (hypothesi de harmonia praestabilita), namely that the considered hypothesis removes human free will (libertatem voluntatis humanae) and thus the ground of theology, morality, and politics” (Rüdiger 1727, d3, pp. 47–48). 89

Rüdiger also responds to Leibniz’s and Wolff’s objections to Physical Influx. First, in response to one of Leibniz’s and Wolff’s main criticisms of Physical Influx, namely that it is incomprehensible how the body can act on the soul (and vice versa), Rüdiger asserts: “Myself and the others who accept some of my doctrines, we can not only understand it, but also [End Page 162] explain it in a much more comprehensible way than Mr. Author can through his pre-established harmony (harmoniam praestabilitam)” (Rüdiger 1727, g3, p. 50). 90 However, instead of providing a positive explanation of how the body can act on the soul, Rüdiger objects to Pre-established Harmony: “I would like to know the sufficient reason why the soul . . . does not move out . . . through the pores of the body and enjoy itself outside the body with a representation of the entire world” (Rüdiger 1727, g3, p. 50). 91 Rüdiger considers and dismisses various possible candidates (e.g., God, the soul, the body) for the sufficient reason of the soul’s inability to move about freely. In response to Leibniz’s and Wolff’s other main criticism of Physical Influx, namely that it violates the law of the conservation of motion, Rüdiger remarks that these laws describe only part of nature, namely its mechanical part, and do not describe the other forces of nature (Rüdiger 1727, s3, p. 57), such as vegetative and animal forces (Rüdiger 1727, u3, p. 58). Similarly, the soul and the body are not subject to this law of nature, “for the body and the soul do not move like machines” (Rüdiger 1727, x3, p. 58). 92 Unfortunately, Rüdiger does not provide any more detailed explanation of how or why the body and soul are exempt from the laws of nature.

Rüdiger develops the following two criticisms of Pre-established Harmony. First, Rüdiger objects to Wolff’s (and Leibniz’s) assertion of intra-substantial causation on the grounds that it is not universally true. His objection is based on the alleged counter-example that it is possible to think of a generous person with a good feeling, and then to get hit by an enemy, and feel hate and revenge without it being the case that the good feeling caused the feelings of hate and revenge (Rüdiger 1727, q4, p. 70). Rüdiger objects to Wolff’s distinction between sensations and other thoughts on the basis of his postulate that “a force that is directed towards something is directed towards it in all its effects” (Rüdiger 1727, s4, p. 71), 93 and he continues to give a number of examples where the exercise of a force (e.g., in a magnet) is universal. The implication this postulate has for Pre-established Harmony is that the soul must direct its thoughts to [End Page 163] the entire world and thus should not experience the limitations of the body that it in fact does. 94

Second, Rüdiger objects to Wolff’s (and Leibniz’s) claim (Wolff [1719–20] 1983, pp. 483–84) that the soul would represent the world to itself even if the world were not at all present. But rather than simply present Wolff’s claim as self-evidently absurd, as Lange, Budde, and Walch do, he provides a number of reasons (Rüdiger 1727, b-f5, pp. 80–82). The most important reason is that it allegedly contradicts Wolff’s own opinion. For Wolff claims that the soul represents the world according to the position of its body, but the soul would not be able to represent the world according to its body because the world would not act on the body and the body would thus not be changed in such a way as to reflect the world as it would have been if it had existed. But since the body is not changed in the appropriate way, the soul would not represent the world, given that the altered state of the body would be reflected in an altered state of the soul which would then not represent the world (but presumably something else). 95

In this context, Rüdiger suggests an interesting diagnosis of the cause of Wolff’s difficulty (other than the reason discussed above, namely that he has a false conception of body and extension). His diagnosis is that since Wolff treats natural and mechanical as synonyms, he cannot explain the influence of the soul on the body since it is not mechanical (Rüdiger 1727, d5, pp. 85–86). He proceeds to list three human activities that he thinks cannot be explained mechanically: i) generationem animalculorum in semine animali, ii) formationem foetus, and iii) systolem and diastolem cordis. Rüdiger’s medical interests are surely guiding his objections here. Rüdiger also discusses a disanalogy between Pre-established Harmony and Physical Influx with respect to the attribution of souls to animals. He first objects that it is a fallacy to infer as Wolff allegedly does (Wolff [1719–20] 1983, p. 492) from the fact that some beings endowed with sense organs have souls to the fact that all beings endowed with sense organs have souls. He then notes that he has developed a probabilistic argument that allows this inference based on the idea that the sense organs of animals would have no purpose if they had no soul. Wolff, however, due to his adherence to Pre-established Harmony, cannot make this inference because the soul does not depend on the body and its sense organs in order to achieve its end. Thus, Physical Influx can give a better account of animals’ souls [End Page 164] because the similarity of sensory organs in animals and humans reveals the necessity of those organs as conduits of information: as points of contact between the external world and the soul. 96

Rüdiger concludes by explaining his own grounds for preferring Physical Influx (Rüdiger 1727, h8, pp. 165–68). He first argues that none of the three causal theories can give a full explanation of the commerce between the soul and the body, whether it be through a direct causal tie, through God, or through a pre-established harmony. On this count, all three causal theories are equal. He then argues that Pre-established Harmony is subject to two difficulties that do not affect Physical Influx: “1) How the soul as an immaterial being can bring about thoughts in the manner of a bodily machine. 2) How the body can speak through its mouth without any causal activity by the soul” (Rüdiger 1727, h8, p. 167). 97 Rüdiger then repeats the standard objection that the soul and body cannot act on each other due to their radical distinctness. After noting that his own view is [End Page 165] not saddled with this problem, he denies that one can know that it is impossible for an immaterial being to act on a body. “For whoever wants to know what is impossible must know all the forces of nature, including their quantity (that is, not only metaphysically (metaphysice), but also scientifically (disciplinaliter)) and whoever knows this is omniscient,” (Rüdiger 1727, h8, p. 166) 98 and since we are not omniscient, we do not know that it is impossible. But the fact that one cannot know that something is impossible does not imply that one is in a position to explain it.

In response to Wolff’s (and Leibniz’s) distinction between certainty and necessity, Rüdiger notes:

The author is always playing with an ambiguity in the word ‘reason’. For we call anything a reason that contributes to the production of something, whether it be 1) the intention of a rational being, or 2) a physical cause without rationality, or 3) a purely mechanical cause. Now when the author says that motivating reasons do not render an action necessary, but rather only certain, I admit it for the first kind, namely where they are the intentions of a rational being, but not for reasons of the second or third kind, since they both bring about necessary actions (or to speak properly motions). Now because according to the author the motivating reasons of the soul belong to the third kind, such actions cannot be anything other than coerced and must be necessary.

(Rüdiger 1727, d13, pp. 252–53)99

In short, Rüdiger claims Wolff’s version of Pre-established Harmony does lapse into determinism in one crucial respect, since some actions that we want to call free have grounds that not only incline but also necessitate.

In sum, while Strähler does not seriously challenge Wolff (or Leibniz) on Pre-established Harmony, Lange, Budde, and Walch press the allegedly [End Page 166] deterministic, fatalistic, and Spinozistic consequences of Pre-established Harmony and are able to raise some other serious objections to Pre-established Harmony (concerning miracles, the imputability of actions, and the union of the soul and the body). Wolff’s replies are almost uniformly uninformative (beyond his original position as stated in his Vernünfftige Gedancken). Rüdiger differs substantially from the other Pietists insofar as he develops Physical Influx in a constructive way and then challenges Pre-established Harmony in various ways on the basis of this prior conception.

III. The Emergence of Physical Influx

From 1723 to approximately 1727 the Pietists’ attack was clearly of primary importance to Wolff. However, to some extent in the 1720s and even more in the 1730s, the discussion centering around Leibniz’s and Wolff’s metaphysics underwent an important shift, since during this time Wolff’s Pre-established Harmony (rather than his entire methodology) came under attack from various members of his own group of followers. In this section and the next, I shall describe how Pre-established Harmony was criticized and how different versions of Physical Influx were developed on the basis of Leibnizian-Wolffian principles.

Samuel Christian Hollmann (1696–1787), Göttingen’s first professor in philosophy, 100 was one of the earliest figures loosely affiliated with the Wolffians to raise serious doubts about Pre-established Harmony. Hollmann first expresses his doubts about Pre-established Harmony in 1724 in his dissertation entitled De Harmonia inter animam et corpus praestabilita. After presenting a systematic explanation of Leibniz’s and Wolff’s doctrines in the first part of his dissertation, Hollmann states his objections to Pre-established Harmony in the second part of the dissertation. Hollmann divides his objections into two different classes: those that pertain to whether Pre-established Harmony can provide a satisfactory account of the diversity of representations that the soul has without taking recourse to the causal efficacy of the body and those that pertain to whether the explanation that Pre-established Harmony provides for corporeal motions is consistent with the imputability of actions. Hollmann develops five objections that fall into the first class. While Hollmann develops these objections in detail and responds to various possible replies a proponent of Pre-established Harmony might make, the main thrust of each of the objections can be briefly stated. The first objection states that if the soul were the sole cause of its perceptions, those perceptions would not be as [End Page 167] disorderly as they are. 101 The second objection states that Pre-established Harmony does not explain “from whence it happens that the soul exactly follows those changes and sudden occurrences that happen to the body, primarily in the brain” (Hollmann 1724a, p. 87). 102 The third objection, like the first, questions whether the order of our sensations and perceptions would be as discontinuous as they are if Pre-established Harmony were true. 103 The fourth objection states that if Pre-established Harmony were true, then whenever the soul reproduced a perception that it had had once before, then the soul would be forced to continue the same series of perceptions now that it had the first time. Since this kind of repetition does not occur, Pre-established Harmony must be false. 104 The final objection states that according to Pre-established Harmony the soul cannot discriminate between new perceptions of things already perceived and memories of those things. 105

Hollmann develops four objections that fall into the second class. In his first and second objections Hollmann (1724a, pp. 95–96, 99) allows that it is possible that God has established the motions of the body such that they proceed according to their own laws without the soul’s causal influence, but then argues that this is not likely, because this account does not explain why the motions caused by various bodies correspond to the soul’s intentions. 106 The third objection states that Wolff cannot admit that the soul has any effect on the body’s motion, [End Page 168] because the body’s motion must be determined by the motions of the bodies that surround it. 107 The fourth objection has Cartesian roots, stating that our linguistic abilities cannot be properly explained purely mechanistically (Hollmann 1724a, p. 101). While these objections may not seem especially noteworthy, it is important to recall that these objections, unlike many of the Pietists’, are objective and philosophically motivated. In fact, Hollmann explicitly distances himself from the Pietists in his Observationes elencticae in Controversia Wolffiana, disputatori cuidam Halensi, ad Vindicandas suas de harmonia inter animam et corpus praestabilita habitas dissertationes in 1724.

Despite the fact that Hollmann does not develop Physical Influx in any positive way and the fact that his objections may not seem to be too threatening to Pre-established Harmony, they did receive some attention. In 1727 Johann Friedrich Schreiber replied with his Litterae ad Samuelem Christianum Hollmannum, philosophiae professorem apud Vitembergenses, scriptae, ubi obiectiones, quas Viri Clarissimi Commentatio in Harmoniae Praestabilitae Systema Leibnitianum exhibet, philosophice soluuntur and from 1726–28 Bilfinger and Hollmann engaged in an exchange 108 in which Hollmann clarifies his arguments and reacts to Bilfinger’s Dilucidationes philosophicae de Deo, anima humana, mundo, et generalibus rerum affectionibus, which had been published two years before. For instance, to Bilfinger’s objection against Physical Influx that the mind and body cannot interact due to a lack of proportion and homogeneity between the two, Hollmann responds that a proportion can arise between two heterogeneous things if there is a third thing with which both are homogeneous in some respect. 109 After Bilfinger’s lengthy point by point response, Hollmann then comes to admit that the arguments he presented in his dissertation do not have the force that he initially thought: “I admit that I have thus been convinced [End Page 169] that those arguments that I had once given against Pre-established Harmony in my two dissertations just like those doubts by which in the Dissertatione Epistolica, given by you, seemed to be remaining, in no way prevail against that system, nor do they show its physical impossibility as I was previously persuaded” (Hollmann 1728, p. 61). 110 Despite this admission, however, Hollmann still holds Physical Influx to be more probable, because “according to the system of physical influx, all things can in fact be more easily understood. For the sufficient reason of ideas is not in the soul, but in the influx of sense ideas into the soul that themselves have their sufficient reason in fact in bodies, existing outside us, and in their various modifications and in the various approaches to the senses” (Hollmann 1728, p. 65). 111 In this way Hollmann suggests that a Leibnizian-Wolffian could reasonably refrain from accepting Pre-established Harmony and hold Physical Influx, though Hollmann recognizes that he has neither given any direct arguments for his belief nor developed his own positive theory.

The other Wolffian who plays an important role in questioning Pre-established Harmony and initiating attempts at giving a positive explanation of Physical Influx is Johann Christoph Gottsched (1700–1766). 112 Gottsched is now best known primarily as the first major literary figure of the German Enlightenment (and for his dispute on aesthetics with Bodmer and Breitinger). However, early in his career Gottsched produced a number of philosophical works that resulted in his being offered a professorship in philosophy at Leipzig. In particular, his second and third dissertations, Vindiciarum systematis influxus physici (1727–29), were devoted precisely to the issue of Pre-established Harmony and Physical Influx, where he is concerned to defend Physical Influx. Then, in his Erste Gründe der gesammten Weltweisheit (1733–34), his popularization of Wolff’s Vernünfftige Gedancken, he again addresses the issue of Pre-established Harmony and Physical Influx, once again defending Physical Influx, albeit in a somewhat weaker and unofficial way.

The Vindiciarum systematis influxus physici divides into two parts. The [End Page 170] first part contains primarily an historical account of the three causal systems, while the second part develops an extended defense of Physical Influx against the objections primarily by the Cartesians. 113 In particular, Gottsched considers the following objections. First, a Cartesian might object to Physical Influx on the grounds that one cannot perceive clearly and distinctly how the mind and body could act on each other, since their natures are radically distinct (Gottsched 1729, pp. 34–35). Gottsched responds to this objection by noting not that there are many things that we do not understand (as, for instance, Walch does), but rather that we have an insufficient account of what it means for the soul to think and the body to be extended. Even if it is clear that thought and extension are the essences of the soul and body, it does not follow that all of the soul’s and body’s properties can be derived from their essences. Therefore, the objection that physical influx cannot be derived from the natures of the soul and the body loses its force. Gottsched proceeds to reformulate the Cartesian objections in a variety of forms and to respond to the fault in each one. For example, Gottsched refines the Cartesian objection as follows: “Whatever can be understood clearly and distinctly without another such being can exist without that other being . . . and I can conceive of the mind clearly and distinctly without the faculty of motion” (Gottsched 1729, p. 36). 114 Gottsched replies to this objection by denying the universality of the first proposition on the grounds that we do not have complete and adequate notions of all things.

Gottsched then considers the objection that Physical Influx violates the law of the conservation of motion. He first notes that Descartes simply assumes (on the basis of its intuitive appeal) that it is impossible for thinking to subsist with motive force in the same subject at the same time. Further, Gottsched has already called into question Descartes’s further grounds for this claim, namely that one cannot clearly and distinctly conceive of thinking and motive force in the same subject, because according to Gottsched we have an insufficient account of both the soul and bodies. However, Gottsched continues by noting that the law of motion that Descartes (and the Cartesians) thinks Physical Influx violates, namely the law of conservation of motion, has been shown (by Leibniz) to be false. What is conserved is not motion, but, as Leibniz argues, motive force, which is measured by the mass of the body times the square of its velocity. [End Page 171] Gottsched then considers whether Physical Influx violates this ‘corrected’ law of nature. In justifying his negative answer, he uses an example of a taut bow. The tension in the string when it is drawn back by an arrow held in one position, so that it is at rest, contains, Gottsched claims, the same amount of motive force as does the motion of the arrow when it is released, despite the fact that the amount of motion in the world is clearly not the same in the two cases. Thus, Gottsched can argue by analogy that according to Physical Influx the soul can add motion to the universe or the motion of a body can cause an idea in the soul (possibly diminishing the amount of motion in the universe) without violating the ‘corrected’ law of conservation. The important requirement is that the motive forces of the body and the soul remain constant regardless of whether they are impeded by external actions or not, that is, whether they result in “new” motions. Given that it is not obvious that Physical Influx violates this requirement, this objection to Physical Influx loses its force. In this way Gottsched develops an interesting reply to one of the most important objections raised against Physical Influx. Moreover, Gottsched manages to do so on the basis of Leibnizian principles, since his acceptance of Leibniz’s principle of the conservation of motive force is crucial to his response.

Still, Gottsched’s defense of Physical Influx does not go beyond a defense; his main goal in these two dissertations is merely to defend Physical Influx from some of the objections that have been or might be raised against it. He does not develop any positive reasons for accepting Physical Influx rather than Pre-established Harmony. Gottsched does, however, further develop his version of Physical Influx a few years later in his Erste Gründe der gesammten Weltweisheit. The two main points that are novel in this work are the following. First, Gottsched responds to the other main criticism that Leibniz raised against Physical Influx, namely that it is incomprehensible how physical influx could occur, e.g., that an accident could migrate from one substance to another. Gottsched notes (§1067) that “the word influence (‘Einfluß’) is taken in a metaphorical or ‘verblümtem’ sense” (Gottsched [1733–34] 1983, p. 582). 115 In other words, Gottsched is pointing out that ‘influence’ (or ‘influere’ which is the Latin term Wolff generally uses) is to be taken not literally as a flowing (of, e.g., a liquid), but rather in terms of the capacity or power of a substance to act directly on another substance. Since, as we shall see below, all of the later major proponents of Physical Influx assume that a substance has such a [End Page 172] capacity to act on other substances, the fact that Gottsched suggests such a force or capacity as primitive represents an important development.

Second, Gottsched now advances some tentative arguments in favor of Physical Influx. Gottsched starts with a fact admitted by Leibniz and Wolff, namely that the soul’s sensations depend on the body’s position in the world. Accordingly, if the soul desires to bring forth new sensations (which Leibniz and Wolff admit in the guise of appetition), then it must change the body’s position in the world, which Gottsched interprets as requiring causal interaction. 116 While this argument begs the question by assuming without argument that the dependency relationship between the soul and the body must be causal, Gottsched can be credited for requesting that the defender of Pre-established Harmony give plausible explanations of how the soul and the body stand in such a close relationship while still denying any causal influence. However, it is worth pointing out that Gottsched himself does not attribute too much weight to these considerations. For after introducing the three causal theories he remarks:

None of the three is completely explained or demonstrated; each one of them still has its difficulties: Thus each person can maintain whichever one is most pleasing. However, for me it has always seemed: that one does not have reason to reject the oldest and most common opinion of natural influence until one has completely refuted it and demonstrated its impossibility. At this point this has been done by no one.

And after presenting another argument in favor of Physical Influx he notes at the end of the section on this topic: “Yet I present all this only as mere speculation and do not decide which opinion, with a more mature knowledge of the soul and the body, will gain the upper hand with time” (Gottsched [1733–34] 1983, p. 588). 118 At the same time, in later editions of this work he refers back to his dissertations, indicating that he has not rejected Physical Influx in favor of Pre-established Harmony. Thus, in his popular Erste Gründe Gottsched seems to accept Physical Influx as an [End Page 173] unofficial or private opinion, though he has contributed in significant ways to the defense and development of Physical Influx. 119

IV. The Full-Fledged Development of Physical Influx

The decisive year for Physical Influx is 1735, for in this year Martin Knutzen (1713–51) and Johann Peter Reusch (1691–1754), both Wolffians, take an official and unambiguous stand on the issue in favor of Physical Influx. Knutzen, 120 who is now known generally (if at all) because he was one of Kant’s teachers at the Albertina Universität in Königsberg, published a revised version of his dissertation (which he defended in 1733) as Systema efficientium causarum in 1735, which due to its considerable influence was reprinted in 1745. This work is of special significance, because in the course of its three parts and 210 pages it not only defends Physical Influx from the objections traditionally raised against it (as Gottsched does), but also presents in a clear and systematic way a number of arguments for Physical Influx that are squarely based on Leibnizian principles. Though Knutzen presents numerous arguments, let us consider briefly two of the most forceful ones. 121

The strategy of Knutzen’s first argument for Physical Influx is to argue that intra-substantial causation implies inter-substantial causation. The specific instance of intra-substantial causation that Knutzen uses to carry out this strategy is the capacity a simple being has to move itself. Knutzen argues as follows:

§. XXVIII. A force [of something] to move itself involves in reality a force of moving another as well.

A force of moving that brings it about that any being changes its own proper place without the force of moving other things that surround it cannot be conceived, but rather it is necessary that after positing one the other is given at the same time. For a force of moving that brings it about that a being changes its own place does not exist except as a conatus for changing its own place (§. 24.) i.e. for occupying a place distinct from the one that it now occupies, yet one that is still continuous to it (§. cit.). But other coexistent things that surround the movable [End Page 174] thing on all sides hold a place distinct from the place of the movable thing, since two distinct beings cannot be in one place at the same time (§. 23.): therefore, a being endowed with the force of moving itself strives to push things to another place, if they resist. But if in truth they are also supposed to yield spontaneously, nevertheless, that which is already participating in progressive motion exerts itself in the way which is required to complete the motion beyond itself or to push things to another place. Because resistance is to such a degree the occasional cause of motion, it does not add anything to the intrinsic force: Therefore, a being that moves itself enjoys the effort of changing the place of coexistents or the force of moving other things (§. 24.). Therefore, the force of moving itself without the force of moving other things cannot be conceived, but after the one has been posited, the other is posited at the same time.

(Knutzen [1735] 1745, pp. 91–92)122

In short, the argument is that if, as Leibniz and Wolff assume, a being possesses the force to change its place, 123 and the change of place of one body implies the change of place of another body, then the force to change its own place implies, now contra Leibniz and Wolff, the force to change the place of another body. 124 [End Page 175]

Knutzen’s second argument for Physical Influx is based on the attribution of resistance to simple beings:

The same can also be demonstrated another way: simple elements are impenetrable, according to the opinion of the illustrious Leibniz who asserts that all finite substances are impenetrable. See his Letter to Cl. Wagner p. 201. Tom. I. Epistl. Edit. Kortholtianae. Hence, it cannot be the case that one substance is in the place of another. Therefore, there is something real, by whose force one simple excludes another and pushes up against (it), lest the other invade its place. For since it is most certain that simples are moved (§. 27.) and that distinct simples are not moved according to an opposite line of direction, consequently it is impossible that they penetrate each other mutually, or rather what we may gather from the conflict of bodies and their collision that in fact they are carried in a contrary direction mutually away from each other; it follows in this case that one must hold that either simples penetrate each other mutually, which goes against Leibniz’s assertions, or if they resist each other mutually, they must act on each other mutually. Q.e.d.

The basic idea underlying this argument is that impenetrability is intelligible only if one substance is attempting to penetrate a second substance, whereby the second substance is said to be impenetrable in virtue of resisting the first substance. However, the argument continues, how can one substance be said to resist another substance if not causally? That is, resistance is surely a causal term, and a substance cannot resist itself, so that if resistance (or impenetrability) is a real property of substances, then there must be interaction between substances. [End Page 176]

Not only does Knutzen present arguments in favor of Physical Influx, arguments, it should be noted, that are at least in intent based on principles that Leibniz and Wolff would accept, but Knutzen also defends Physical Influx in interesting ways against the objections raised by Leibniz, Wolff, and Bilfinger. First, he develops a new model of inter-substantial causation. While Gottsched seemed to hold that only one force was required for inter-substantial causation, Knutzen suggests that two forces are required. Second, in response to the objection that Physical Influx should be rejected on the grounds that an accident cannot migrate from one substance to another, Knutzen states:

While the body acts on the mind according to the system of physical influx, it does not pour ideas of external things into the mind, nor the force of representation; but rather it modifies only the force of the mind and its substance in such a grounded way that representation is caused in the mind. But the mind, when it acts on the body, does not pour a moving force into it, but rather only modifies and directs with its actions those things to the extent that are present in corporeal elements in such a way that finally motion is produced in the body. For ideas and the force of representation are either accidents or substances. If they are accidents: they cannot be poured into the mind by the body and they cannot be transferred into the mind by a certain local motion from the body. For accidents do not migrate from subject to subject (§. 791. Ontol.). But if you suppose that they are substances: similarly such a transition cannot be granted; because the mind is a simple substance (§. 18.), but such a first substance cannot be the receptacle of many other substances. Therefore, neither ideas nor the forces of representation can be poured from the body into the mind. However, because representations of external things appear in the mind through the action of the body (§. 40. not.): nothing is left over than that as the body while it acts on the mind, modifies its force and the substance such that representations of external things in fact appear or are caused in the mind. For a similar reason it can be shown that no moving force can be transferred from the mind to the body: and so through the action of the mind only those forces that they recently demonstrated as being present in its elements (§. 196. Cosmol.) are modified and directed due to certain reasons such that finally determinate motion is produced in the body through the determination of these forces.

(Knutzen [1735] 1745, pp. 145–47)126 [End Page 177]

Here we see even more explicitly than in Gottsched that defending Physical Influx requires assuming that a substance has a power or force to bring about changes in another substance. Further, Knutzen expressly claims that two forces are required for changes to occur: one that instigates the change and another in the substance in which the change is to occur that i) is modified by the activity of the first force and ii) produces the property in itself. Accordingly, Knutzen attains a degree of sophistication in his model of inter-substantial causation not present in earlier proponents of Physical Influx.

Knutzen also responds to the other main objection raised against Physical Influx, namely that it violates the laws of the conservation of motion. Knutzen’s main response to the objection that Physical Influx violates the law of the conservation of motion is to deny that the law holds for mind-body interaction. He notes that the law has been proven only for elastic bodies, not for inelastic bodies, much less for the mind and the body. This is part of what he means when he emphasizes: “I deny . . . that it follows from Physical Influx that a certain quantity of living forces is not conserved in the collision of bodies amongst each other” (Knutzen [1735] 1745, p. 177) 127 and “as long as it has not yet been shown and cannot be shown that this law of motion about conserving a certain quantity of living forces is not only dictated for bodies acting on each other mutually, but also for the mind acting on the body and vice versa, there is absolutely no objection injurious to Physical Influx” (Knutzen [1735] 1745, p. 178). 128 Indeed [End Page 178] Knutzen even provides a reason why this law should not hold for the mind. Since Leibniz derives the law of the conservation of motion from the law of inertia (“that any body remains in its state of rest or uniform motion in a direction unless it is forced to change its state by an extrinsic cause”), and “it is most evident that the mind does not at all remain in its state of rest and uniform motion in a direction until forced to change its state by an external [cause]” (Knutzen [1735] 1745, p. 182) 129 (i.e., the law of inertia does not hold for the mind), there is no reason for the conservation law to hold for the mind. 130 Given that Knutzen provides several arguments for Physical Influx based on Leibnizian principles, develops a more sophisticated model of inter-substantial causation, and responds in novel ways to various objections raised against Physical Influx, Knutzen’s achievements are quite impressive.

The idea of defending Physical Influx from a Leibnizian standpoint seems to have been “in the air” because Reusch, a professor of philosophy in Jena, undertakes such a project in his Systema Metaphysicum in the very same year that Knutzen does (1735). Unlike Knutzen’s treatise, which is devoted entirely to the issue of Physical Influx, Reusch’s Systema Metaphysicum is a metaphysics textbook that covers the wide range of topics treated in Wolff’s Vernünfftige Gedancken. In the section on the commerce between the mind and the body, Reusch starts by describing some of the features that are necessary for any of the causal theories to be possible. Accordingly, there must be a sufficient reason for the commerce between the mind and the body (Reusch [1735] 1990, p. 526), one need not have already demonstrated the truth of the causal theory (Reusch [1735] 1990, p. 527), it must account for our experience of a correlation between certain changes in the mind and certain changes in the body (Reusch [1735] 1990, pp. 527–28), it cannot be inimical to freedom, Scripture, theology, or moral philosophy (Reusch [1735] 1990, pp. 528–29), and it must be compatible with the essence or nature of the soul (which he defines along with Leibniz and Wolff as a simple being endowed with a representative force). He also suggests that monists, materialists, idealists, and skeptics have no need of any of these causal theories (Reusch [End Page 179] [1735] 1990, pp. 532–34). Presumably, all three causal theories meet these requirements.

Reusch then defines Physical Influx as asserting that one substance determines changes in another such that the latter changes its force with respect to its tendency or impetus. In his explanation of this definition, like Knutzen, he shows a real sensitivity to Leibniz’s objection about the intelligibility of physical influx, namely that an accident cannot migrate from one substance to another. For he says: “No force is transferred from one substance into another through influx, but certain new limitations arise through the proper substantial force that is only caused contingently by a substance. Because such an influx cannot be conceived in bodies in any other way, inasmuch as of them one also does not transfer any force into another through action” (Reusch [1735] 1990, p. 534). 131

Reusch then explains why he thinks that Physical Influx is probable, and thus preferable to Pre-established Harmony. After briefly noting that it satisfies the conditions stated above, Reusch suggests that Physical Influx is “certainly natural and has no disadvantages” (Reusch [1735] 1990, p. 536). 132 However, what is of interest is Reusch’s further explanation:

Either no action of a created substance on another and therefore no action of body on body is admitted, because it is contrary to the beliefs of those who assert one of the other systems, or there is no reason why this system of causality [physical influx] is impugned by the commerce of the mind and the body: for the action of one body on another body is ultimately resolved into the actions of simple substances or elements.

(Reusch [1735] 1990, pp. 536–37)133

In other words, one might not accept Physical Influx because one is already committed to one of the other systems (which begs the question). However, [End Page 180] what Reusch is implicitly arguing here is that any problem that might hold for the action of the body on the soul (and presumably vice versa) dissolves because the body and any of its actions must be ultimately reduced to the actions of the simple elements (or monads) that constitute the body, and this reduction eliminates the heterogeneity of the mind and the body. Accordingly, contrary to the objection raised by proponents of Pre-established Harmony, the distinctness of mind and body does not prohibit causal interaction.

After explaining Occasionalism and some of the objections typically raised against it, Reusch turns to Pre-established Harmony. While Reusch deems Occasionalism improbable (due to the perpetual miracles Leibniz claims it is committed to and its conflict with the status of the laws of nature), he is much more gentle with Pre-established Harmony, stating that “it does not seem probable to me” for two reasons. First, “it disregards the laws of change in the universe (§796ff.), and it destroys the action of a simple substance on another simple or a composite, and vice versa, of it on the former; however, it can both happen (§§576, 578, 581ff.) and be necessary, if there should be any action of a creature on a creature (§545ff.) and the existence of bodies would be all right (§572)” (Reusch [1735] 1990, p. 553). 134 Interestingly, tracing Reusch’s reference to §576, which then refers in turn back to §555, we find that Reusch, like Knutzen, thinks that one must accept the action of simples on each other due to the property of resistance. 135 Reusch goes beyond Knutzen, however, insofar as he suggests that the simples must act on each other if they are to come together to form bodies in the first place. Once such actions have been admitted, there seems to be no reason to resist attributing actions between the simples and the complexes they compose.

Second, Reusch objects to Pre-established Harmony on the following grounds:

After having posited the system of pre-established harmony the existence of all bodies seems superfluous, and therefore contrary to the [End Page 181] divine wisdom because it chooses nothing that is frustrated. For in natural theology it is demonstrated that the ultimate end of finite entities and creation is the illustration of the divine glory. Because this obtains, if the divine perfections assume intelligent creatures according to the motives of their actions: bodies, or beings lacking intellect (§672), do not immediately promote the glory of God, but at most mediately, while they provide an occasion to beings endowed with intellect for knowing the perfections of the Deity. But in the system of pre-established harmony rational substances acquire all knowledge by power of its aid without body and bodies have only the reason of exemplar causes with respect to sense ideas (§805ff. 292): hence, because external exemplar causes or efficient causes outside ideas exist as superfluous or frustrated, if the idea of them is sufficiently accurate (§293), there seems to be no sufficient reason present why bodies should exist outside the infallible intellect of God.

(Reusch [1735] 1990, pp. 553–54)136

This objection turns out to be rather influential in the following debate. The idea is that bodies are completely superfluous according to Pre-established Harmony because they do not honor God in either an immediate or a mediate way. For i) they do not know the perfections of God nor ii) are they causal conditions for any being’s coming to know the perfections of God. While Reusch clearly intends this objection to be an important reason for rejecting Pre-established Harmony, its force is limited to dualists or those who want to assert the reality of bodies. Another way of taking this objection is as an argument whose goal is to show that if one accepts Pre-established Harmony, then one must also accept idealism. One might have thought that Pre-established Harmony leaves open the question as to whether one is an idealist, a materialist, or a dualist. If Reusch’s objection is cogent, a proponent of Pre-established Harmony must accept idealism. [End Page 182]

While Knutzen and Reusch both defend Physical Influx in rather similar ways, their criticisms of Pre-established Harmony are at times similar in an interesting way too. For both consider more clearly than does Wolff the relationship between simples and the bodies they compose. Leibniz is clear on this issue insofar as he emphatically underscores that there is a pre-established harmony between the law of final causes that governs simples and the law of efficient causes that governs bodies. Leibniz is also clear that there is some kind of founding relationship between the simples and the bodies that are formed by the composites of the simples. However, and this is where Knutzen and Reusch’s objections may have real force against this position, nothing Leibniz and Wolff say prohibits interpreting this ‘well-founding’ relationship as a causal relationship because the simples are necessary conditions for their composites, just as a cause is a necessary condition for its effect. 137 Further, once one has allowed causal relationships between simples and composites, it is much easier to allow causal relationships between simples and between composites, that is, there is little barring one from adopting a full-fledged version of Physical Influx. In fact, one of the significant features of both Knutzen’s and Reusch’s discussions is that they consider the issue not only in its specific mind-body form, but also in complete generality, namely how it is possible for one being to act on another at all. This feature distinguishes them from many other participants in the debate.

Accordingly, Knutzen and Reusch represent a turning point in the debate between the proponents of Pre-established Harmony and Physical Influx. Both present arguments for Physical Influx (though Knutzen’s are much more forceful and developed in more detail) and both raise serious objections to Leibniz’s and Wolff’s position, objections that are nonetheless based on Leibnizian principles. Finally, they develop more sophisticated models of physical influx that deal in interesting ways with Leibniz’s objections to Physical Influx. For all these reasons Knutzen and Reusch play a crucial role in the ultimate success of Physical Influx. 138

V. A Final Attempt at Rescuing Pre-established Harmony

In 1737 Lange once again attempted to have Wolff’s doctrine of Pre-established Harmony condemned by petitioning the king. The king set up an independent committee to decide the matter and appointed Johann Gustav [End Page 183] Reinbeck as the head of the committee. After much deliberation and despite the fact that Reinbeck himself held Physical Influx, in his report he declared that one should tolerate Pre-established Harmony. 139 Accordingly, Lange’s attempt backfired and once again Pre-established Harmony and Physical Influx received sustained attention. 140 In particular, two faithful Leibnizian-Wolffians, Alexander Gottlieb Baumgarten (1714–62), professor of philosophy first at Halle, then at Frankfurt on the Oder, and Georg Friedrich Meier (1718–77), professor of philosophy at Halle, attempted to rescue Pre-established Harmony, primarily by returning to a more Leibnizian position.

In 1739 Baumgarten, who is now better known for his work in aesthetics (in particular due to his attempted synthesis of Gottsched’s and Bodmer’s positions), published his metaphysics textbook, Metaphysica. 141 In it Baumgarten refers to the simples that compose bodies as monads and, contrary to Wolff’s agnosticism, he clearly attributes representative force to all monads. However, Baumgarten goes beyond a mere restatement of the received interpretation of Leibniz by making a sustained attempt at explaining how we can still talk as if there were causal interaction between substances even if there is none. To this end he defines influx as follows: “A substance flows into a substance distinct from it by acting on it, therefore influx (transeunt action) is the action of a substance on a substance distinct from it” (Baumgarten 1739, p. 71). 142 Then, in his chapter on cosmology, he states that “all monads of this world mutually determine the place of simultaneity, the time of succession, §281, 85, flow into each other mutually, §211, are posited in conflict, §213. Therefore, there is universal influx and conflict in this world, §48, 306” (Baumgarten 1739, p. 112). 143 Thus, he seems to be admitting Physical Influx amongst monads. However, taking recourse to Leibniz’s distinction between ideal and real grounds, Baumgarten attempts to avoid this consequence (that is, he allows one to [End Page 184] continue talking as if there were causal interaction) by distinguishing between real and ideal influx. 144 Physical Influx posits real influx, whereas Pre-established Harmony posits only ideal influx. Earlier in the Metaphysica Baumgarten defines ideal and real influx as follows: “A passion or influx is called ideal if the passion of a substance on which another acts is at the same time an action of the patient itself. A passion or influx is real if the passion is not an action of the patient” (Baumgarten 1739, p. 71). 145 In other words, if a substance acts on itself, then ideal influx is present and Pre-established Harmony holds. 146 Accordingly, we can say that there is influx between substances as long as we mean only that there is ideal influx between them, and ideal influx means that each substance acts only on itself.

Baumgarten also presents the following argument for Pre-established Harmony:

Because the necessary condition of universal pre-established harmony is its possibility in a perfect world, what is to be demonstrated can be demonstrated of pre-established harmony by §462. Another way it is thus clear: from any single monad of any world the parts of the world to which it pertains can be known, §400, therefore also the changes of a single world, §354, 155. However, such are all passions of any monad of the world, which (monad) it experiences from another monad of its world, §210. However, a monad is a passive force, §199. Therefore, that monad that is passive with respect to another monad of the world is the reason of its passions, and a single part of it, §354, 155, this is a sufficient reason of its changes, §14, 21, and therefore its passion is given at the same time as is the action of the patient, §210. Therefore all passions of the monads of any world that they experience from other monads of the world are to this extent ideal, §212.

(Baumgarten 1739, p. 123)147 [End Page 185]

In the next section (§464) Baumgarten argues that since a world containing only ideal influx has the greatest connection (because everything has ideal influx with everything else), and since God will choose to create the most perfect world, that is, the world with the greatest connection, God will choose to create the world according to Pre-established Harmony. In short, Pre-established Harmony is true, because it alone brings about a world with the most harmony and thus the most perfection.

While Baumgarten presents his views on Pre-established Harmony and Physical Influx within the context of his general metaphysics textbook, Meier, his student, devotes an entire treatise to the issue in 1743, namely Beweis der vorherbestimmten Übereinstimmung. Accordingly, although Meier follows Baumgarten’s main view, he is able to develop it in more detail. Thus, he feels justified in advancing Pre-established Harmony as a theorem rather than as a probable hypothesis, because he adduces both objections to Physical Influx and Occasionalism and arguments in favor of Pre-established Harmony. While his positive argument for Pre-established Harmony mirrors Baumgarten’s, Meier develops several novel objections to Physical Influx. First, he argues that

All harmonious changes of the substances of this world can be known from other finite substances. Thus, they have their reason in other finite substances that are present beyond those whose state is changed in an harmonious way §9. That change of state that has its reason in another thing is called a passion, and thus all harmonious changes in this world are passions. These passions have their reason in other finite substances. All harmonious changes in the world are accordingly natural passions §14. A universal influxionist considers all natural passions to be real passions §14. Consequently, a universal influxionist must consider all changes in this world that are produced naturally to be real passions. Accordingly, not a single change of state can be produced through a substance’s own force in which this change is effected, thus it behaves merely passively in this case §11. . . . But what influxionist would admit this?

(Meier 1743, p. 72)148 [End Page 186]

The main idea behind Meier’s argument is that by defining real and ideal influx as he does (along with Baumgarten), he positions Physical Influx in such a way that it ends up excluding intra-substantial causation. Since it may seem that there are instances of intra-substantial causation, Physical Influx would have to be rejected if it is in fact committed to excluding intra-substantial causation. 149 It is apparent, however, that Meier’s only explicit reason for holding that Physical Influx excludes intra-substantial causation is his (and Baumgarten’s) definitions of real and ideal influx.

Meier also develops the following objection to what he understands by physical influx:

When a finite substance acts, its inner state is thereby always changed. Or: whenever a finite substance acts, an inner state is produced in it by this action that was not to be met with in it before it acted. Assume the opposite. A finite substance is supposed to act, but not produce through this action any determination in itself. A determination is produced by every action §46. Consequently the determination brought about by this substance would have to be produced outside of it. Accordingly, one can view this substance in a twofold state, prior to its action and while it acts. Accordingly, if it were not itself changed by its action, it would, when it started the action, remain completely the same substance, without the smallest change, that it was before it acted. Now because the consequences remain the same when the grounds are the same (posita eadem ratione ponitur idem rationatum), the assumed substance, or force, would bring about the same effects in this, its twofold state. Before the action it did not cause the determination that was supposed to be produced, otherwise it would not need to act §46. [End Page 187] Consequently, it will also produce no determination in the other state, when it is in the process of action, which contradicts not only the concept of action but also what would have to be assumed if one wanted to deny my theorem.

(Meier 1743, pp. 88–90)150

The argument here is somewhat convoluted, but the general idea is that inter-substantial causation is impossible without intra-substantial causation, because insofar as one substance changes the state of another substance it must thereby also change itself. For if it did not change itself, then it could not have changed the other substance, given that the same grounds continue to be present in the first substance and one set of grounds cannot be responsible for first one set of determinations and then a contrary set. Though Meier has given no reason why intra-substantial causation precludes inter-substantial causation (which is what would be required for the argument to have any additional force against Physical Influx), he may be assuming that the presence of both intra-substantial and inter-substantial causation is tantamount to causal overdetermination, which is to be avoided.

Meier presents a further reason for rejecting Physical Influx:

I first want to consider the smallest substance or force, and show of it that it cannot act physically on another. It is self-evident, that this substance is finite, because God possesses the largest force. If one wanted to object that no substance is really present that would be the smallest, I will admit this for the sake of the general harmony [End Page 188] in the world. Instead, let one assume a greater substance that, however, uses its force only to the smallest degree. One will surely admit this case. Cannot all larger actions and forces rightly be viewed as a summation of the smallest actions and forces? Thus posit the smallest force, or a greater substance that, however, uses its force only in the smallest degree. This substance can undertake only the smallest action §47. But can this action be real influx? Let us assume it for a while. Through this smallest action a determination in the smallest substance itself is produced §49, 50. This determination cannot, however, be smaller than the smallest. The smallest is precisely the one which, if it were smaller, would contain a contradiction. . . . Thus, if the smallest action of a finite substance could be real influx, then, through the smallest action, at least two smallest determinations would have to be effected, which is impossible §47.

(Meier 1743, pp. 92–93)151

Meier proceeds to point out the further, albeit related difficulty that if a substance brought about the smallest effect, but the smallest effect entailed a change in the acting substance, then the smallest effect would not be the smallest effect (since there would be two effects where each of these two effects taken in isolation is clearly less than when taken together), which is a contradiction. Such arguments clearly go well beyond any considerations Leibniz presents against Physical Influx.

Meier also provides further support for Baumgarten’s argument for Pre-established Harmony that is based on the world’s perfection. Even if [End Page 189] one grants that the perfection of the world is to be measured by the amount of harmony contained in it, one might still wonder why the world has greater harmony according to Pre-established Harmony, or, alternately, why it has less harmony according to Physical Influx. Meier points out that the world has less harmony according to Physical Influx because there are “many gaps in the world,” (Meier 1743, p. 134) 152 that is, each substance contains the grounds only for some other substances, namely those on which it acts immediately, which will presumably be fewer than all substances in the world. According to Pre-established Harmony, however, every substance completely expresses, mirrors, or contains an ideal ground for every (state of every) other substance.

Meier also gives a different explanation of the ideal influx that Baumgarten introduced. Part of the intuitive appeal of ideal influx or an ideal ground is that due to the fact that every substance represents the entire world, every substance has a representation or idea of what properties are true of every other substance at any given time. Accordingly, since each substance contains complete information on every other substance without any causal or real interaction, the connection between this and all other substances consists in ideas or is ideal rather than real. Thus, it seems that the difference between a real and ideal ground (or influx) is that in the former case the relation between substances is mind-independent, whereas in the latter case the relation is mind-dependent. However, unlike Baumgarten (who seems to accept this line of reasoning), Meier explains the real-ideal distinction as follows:

This influx is not called ideal because it is as if there were no real influx, and it were only a mere representation in the soul that has no actual object outside of the soul, or as if it were just a mere figment of the mind. Rather it is called this because it can be explained on the basis of representations. And, for one, on the basis of concepts that, from eternity, God created of these substances that act on each other ideally.

(Meier 1743, p. 24)153

Accordingly, Meier provides a somewhat fuller explanation of why an ideal influx or ground is not purely fictitious or illusory. In this way Meier hopes [End Page 190] to preclude the charge that ideal grounds are an ad hoc solution to the apparent connection between substances.

Baumgarten’s and Meier’s return to a more Leibnizian position represented an important attempt to save Pre-established Harmony. And their attempt was surely influential in some important circles. For instance, Stiebritz and Baumeister both continued to maintain Pre-established Harmony throughout the 1740s, 154 and as late as 1755, one of Prussia’s most popular and influential proponents of the Enlightenment, Moses Mendelssohn, still adhered to Pre-established Harmony. 155

VI. Physical Influx as the Standard View

Despite Baumgarten’s and Meier’s efforts, however, Physical Influx became the standard doctrine. In order to see how this occurred, consider briefly how Physical Influx was maintained by two of the more important German philosophers in the 1740s and 1750s, namely Christian August Crusius (1715–75), professor of philosophy in Leipzig, and Joachim Georg Darjes (1714–91), professor of philosophy in Jena. 156

Crusius, who was a student of Rüdiger and a colleague Gottsched, wrote his Entwurf der nothwendigen Vernunft-Wahrheiten in 1745 and his Weg zur Gewißheit und Zuverläßigkeit two years later in 1747. 157 In his Entwurf Crusius raises the following objection to Pre-established Harmony:

Any connection of finite things that is to be a real unio existentialis outside thought must rest on a causal connection of things due to which at least one must act on the other, but also both can act on each other reciprocally as well as be passive with respect to each [End Page 191] other. For there is otherwise nothing else outside thought that can provide a ground of connection between complete things. But as soon as one takes this away, then one must connect them only in a concept in the understanding, i.e. the things thus have either no or a merely ideal connection. Consequently, I cannot, e.g., admit that those who believe Pre-established Harmony leave a real connection between body and soul. . . . Their connection is only ideal even with respect to God. One cannot even say that they are connected by the intervention of God. For then at least the arrangement (‘Einrichtung’) of the essence (‘Wesen’) of the body and soul would have to be attributed to God. But the defenders of Pre-established Harmony can never say this in the Leibnizian sense, because they do not leave God any honor beyond bringing the essences of substances into existence, rather than arranging them, because all beings are to be eternal. Thus a mere correspondence rather than a real connection remains.

(Crusius 1745, §94, p. 160–61)158

Crusius’s main argument 159 is that the ground of a real connection must be a (necessary) causal connection, because nothing other than a causal connection can provide a ground for a real connection. Yet in order not to beg the question against Pre-established Harmony, Crusius must explain why, [End Page 192] e.g., God cannot be a sufficient ground of a real (mundane) connection because a proponent of Pre-established Harmony, such as Meier, will presumably attempt to maintain that God is the ground of real connection. Crusius argues that proponents of Pre-established Harmony can ascribe to God’s action only a mere correspondence 160 between substances rather than a real connection (and dependence), because although God brings beings into existence, God is not responsible for their essences (since their essences are given with necessity in the Divine understanding and cannot be altered by the Divine will). 161 Thus, Crusius is claiming that, according to Pre-established Harmony, although God can bring into existence substances that correspond to each other, God cannot bring into existence substances with a real but non-causal connection.

Crusius also replies to some of the objections raised against Physical Influx. The first objection against Physical Influx that he considers is that allowing minds to act on bodies would turn minds into matter. 162 Crusius, in a way similar to that of his teacher, Rüdiger, replies to this objection that despite their differences mind and matter share a property, namely the general capacity to move (‘General-Eigenschaft’) in virtue of which they can act on each other. The fact that mind and matter have a property in common does not imply that there is no relevant difference between minds and matter (i.e., does not turn mind into matter), because the fact that mind and matter share one essential property (‘General-Wesen’) does not imply that they share all their properties. Accordingly, Crusius attributes a specific difference to each (‘Differential-Wesen’), whereas what is common to both, e.g., the ability of each to cause motion, lies in their general nature. The second objection states that it is not possible for a mind to have the capacity to move a body, since that would violate a mind’s basic nature (‘Grund-Wesen’). His response to this objection is essentially the same as to the first objection. 163 For this objection results from considering the differences between the mind and the body, rather than their general essences. The third objection Crusius considers is the traditional objection raised against both Occasionalism and Physical Influx (by Leibniz and Wolff), namely that Physical Influx would violate both the law of the [End Page 193] conservation of motive forces and the law of the conservation of motion. Crusius’s full reply is novel; he “bites the bullet” and rejects as impossible these particular laws of motion, noting that if they were true, the absurd results would follow that minds could not cause any motion and, as Reusch had noted earlier, that matter would not be able to fulfill the purpose for which God intended them, namely to be a means for rational and free beings. 164 Thus, Crusius turns the argument around and challenges the laws of the conservation of motion.

Crusius also develops his model of inter-substantial causation in a new way. For at §§79–81 of the Entwurf, Crusius provides an explicit and detailed account of basic forces which are instantiations of the basic force a substance has to act on other substances that Gottsched assumed back in 1733. Crusius distinguishes forces as follows:

§79. That which a cause contributes to the production of an effect, it accomplishes either 1) through its mere existence, because through it the existence, or a certain manner of existing, of another thing is made possible, impossible or necessary. . . . Such causes are called existential-grounds. §36 The force thereof can be called the inefficacious capacity of an existential ground (facultas existentialis) . . . Or 2) the cause acts due to an inner property of its essence which is now directed towards the production of this effect: Thus one attributes to it an activity or self-activity. It is called an active cause and its force an active force (Facultas actiua). Thus an active force is a property connected to a substance belonging to its inner essence due to which something else is actual through it. . . .

§ 80. The difficulty found in an object of accepting the action of a cause is called the reaction or resistance. . . .

§ 81. Among active substances an activity can depend in turn on another of which it is an effect. But this series cannot proceed infinitely, but rather one must ultimately come to first actions that [End Page 194] arise from the force of subjects not through another action but rather immediately and are nothing other than the application of the first basic forces themselves. I want to call these basic activities (actiones primas). Two species of these are conceivable. First, such basic activities that persist due to the essence of the substance and that constitute the inner essence of the active substances. . . . Further there is such a species of basic activities that do not constantly act.

(Crusius 1745, §§79–81, pp. 135–39)165

Crusius proceeds to develop the notion of basic forces under various headings. But we can already see that he has progressed to a level of sophistication not attained by Gottsched, Knutzen, or Reusch. 166 In short, he has proposed a full-blown account of Physical Influx, not just a sketch or an outline. Further, Crusius’s account reveals what was of concern in the 1740s, namely not only arguments for Physical Influx and against Pre-established Harmony, but also a more detailed explanation of the model of inter-substantial causation involved in Physical Influx.

In the 1750s Physical Influx continues to be the standard view. For example Joachim Darjes, like his colleague Reusch, defends this position in his metaphysics textbook, Elementa Metaphysices (1743–44). While Darjes does not develop his version of Physical Influx to the extent that [End Page 195] Crusius does, he does nevertheless make a number of points that are noteworthy. First, Darjes introduces a distinction between acting harmoniously and acting in harmony. Two substances act harmoniously if one can understand what the one substance does by considering the action of the other substance (§56). In contrast, two substances act in harmony insofar as one can understand from what occurs in one substance why a certain set of actions and not another occurs in the other substance (§54). Accordingly, the fact that two substances act harmoniously does not imply that they are in harmony (§57). This distinction allows Darjes to describe Pre-established Harmony in such a way that substances act harmoniously, but are not in harmony (§63), and Physical Influx in such a way that substances both act harmoniously and are in harmony, at least in certain respects (§81). After raising standard objections to Pre-established Harmony (e.g., it provides no reason for the actual existence of bodies), 167 he then objects (§62) that Pre-established Harmony is inadequate because it cannot explain on the basis of what is happening in the mind why the body is changing the way it is, given that it does not contain the sufficient reason why the body acts as it does, but only information about how it acts. Accordingly, Pre-established Harmony does not provide a truly sufficient explanation for the changes that occur in the mind and the body.

Second, Darjes, like Crusius, is concerned to develop a more precise account of the conditions under which the mind and the body can act on each other according to Physical Influx. To this end Darjes distinguishes between efficient causes and remote causes (§82), where remote causes are causes that act only after impediments have been removed. He then argues that the mind can act on the body as an efficient cause, but the body can act on the mind as an efficient cause only if the mind ceases thinking altogether. If the mind does not cease thinking, but rather thinks certain thoughts as a result, then the body can act on it only remotely (§85). Darjes explains this limitation of bodies by claiming that bodies are composed of non-spontaneous simples, which are incapable of acting on the mind as an efficient cause in a determinate way. 168 Despite its lack of spontaneity, it can still be an efficient cause, but only insofar as it causes the lack of thought altogether. In this way Darjes hopes to give a more detailed account of how the mind and body can interact according to Physical Influx.

Darjes also responds to the two standard objections to Physical Influx, concerning the nature of ‘influx’ and the conservation of motion. Regarding [End Page 196] the first objection, Darjes simply notes (§83) that he does not hold that any force is literally transferred from one substance to the other; he seems merely to follow Gottsched insofar as he is assuming as primitive the idea that a substance can have a force or power to act on others. Further, he seems to follow Knutzen insofar as in regarding the case of the mind-body interaction he interprets this force in such a way that the body causes the mind’s representative force to be modified. Concerning the second objection, Darjes argues (§84) that Physical Influx per se (or if it is considered abstractly) is not committed to any particular view of the conservation of forces (or the lack thereof). In order for Physical Influx to be consistent or inconsistent with the law of the conservation of motive forces, one must make further assumptions about the conditions under which motive forces can be created, conserved, or perish. From these remarks, we can see that Darjes, like Crusius, is primarily concerned with the details of his version of Physical Influx.

It should be noted that Crusius and Darjes are not the only ones in the 1740s, 1750s, and beyond who are concerned with establishing the proper version of Physical Influx. In addition to these two figures, Hermann Samuel Reimarus (in Hamburg), who was to become famous (with Lessing’s help) for his religious views, as well as Gottfried Ploucquet and Israel Gottlieb Canz (both in Tübingen) develop their own versions of Physical Influx. Finally, it is worthy noting that way off in the East Prussian hinterlands of Königsberg, there is another philosopher toiling away at his own version of Physical Influx, namely Immanuel Kant. 169

Eric Watkins
Virginia Polytechnic Insitute and State University
Eric Watkins

Eric Watkins is currently assistant professor of philosophy at Virginia Polytechnic Institute and State University. He has written extensively on Kant’s metaphysics and epistemology in the context of eighteenth century German philosophy. More recently, he has turned to Kant’s philosophy of science. He is currently researching the relationship between metaphysics and physics in eighteenth century Germany, with an emphasis on Kant’s account.


1. It is worth noting that no detailed consensus is reached by these figures. For example, Wundt tends to divide the reception into three 30 year periods (1690–1720, 1720–50, and 1750–80), with different characterizations of each period. Wolff’s period (1720–50) is divided into Wolff, Wolff’s school, and the battle against Wolff, while the last period (1750–80) discusses man, classes (‘Unterricht’), and independent thinkers (‘Selbstdenker’). Accordingly, Wundt cannot find any overarching general theme that explains the philosophical development during this period. (Zeller’s classification system is similar to, but less sophisticated than Wundt’s.) More recent accounts seem to fare little better, since Wilson seems to move from one topic to another without arguing for any specific connection, and Beck divides the important figures into such groups as “Two Founders of the German Enlightenment,” “A Generation of Epigoni,” and “Philosophers on the Spree,” which, again, makes it difficult to discern any general movement over time or from figure to figure. In other words, the difficulty these general accounts encounter is that by presenting each figure’s general philosophy under radically different headings it is not clear how each figure is answering a question that was generally perceived to be of pressing concern or how each one was reacting to others’ answers to such a question. My “solution” to this problem is to focus on only one issue (the most important issue, I shall argue) in a fair amount of detail so that one can extract from it an accurate, albeit restricted sense of how Leibniz was received (and the difficulties these figures had in understanding Leibniz). This procedure has the advantage that one can be sure that these figures share similar concerns and a certain development can be discerned, though (and this is the disadvantage) no claim to completeness can be made.

2. Traditionally, the other alternative to Physical Influx was Occasionalism, explicitly developed by Malebranche. Occasionalism, like Pre-established Harmony, denies inter-substantial causation, but, unlike Pre-established Harmony, denies intra-substantial causation as well. In short, it denies that any finite substance has any causal efficacy whatsoever. God alone is the real cause of substances and their states.

3. ‘Physical Influx’, ‘Occasionalism’, and ‘Pre-established Harmony’ refer to the theories of physical influx, occasionalism, and pre-established harmony.

4. For a wide range of interpretations of the details of Leibniz’s Pre-established Harmony, see Nadler (1993).

5. In the following, by ‘substance’ I shall always mean ‘finite substance’, unless otherwise noted.

6. See O’Neill (1993) for an account of the views Leibniz may have understood as instances of such a theory.

7. The main objection that Leibniz raises against Occasionalism is that it requires “perpetual miracles.”

9. For a variety of accounts of Leibniz’s view of freedom, see Sleigh (1990), Adams (1994), and Murray (1995).

10. This argument is explicitly formulated in Leibniz’s “A New System of Nature” (1695). For a fuller discussion of these issues, see Garber (1994).

11. The reduction of bodies to well-founded phenomena does not follow immediately from the dependence of bodies on non-extended simples. Bodies could be dependent and fully real. However, other difficulties lead Leibniz to the further step of considering bodies to be merely phenomenal.

12. For an indication of the depth of physics-based and theological considerations in Leibniz, see Garber (1994) and Sleigh (1990), respectively.

13. Wolff eschews calling these simples or simple elements monads.

14. Beck (1969, pp. 256–75) presents various basic respects in which Wolff is actually quite unlike Leibniz. Corr (1975) also addresses this issue. I would add that Wolff differs from Leibniz primarily to the extent that Wolff omits much of the depth of Leibniz’s position (whether intentionally or not is often a difficult question).

15. Invalidly it would seem. Although Wolff’s explanation adds premises such as the Principle of the Identity of Indiscernibles and the position that space and time cannot provide a reason for the distinctness of simples, all of this seems entirely irrelevant to whether things can act on each other or not and to whether everything must be ‘directed toward’ everything else.

16. “Diesemnach richtet sich der innere Zustand eines jeden einfachen Dinges nach den übrigen, die um dasselbe sind. Und stimmen demnach alle (§593–594) mit einander überein: wodurch die Vollkommenheit im zusammengesetzten erhalten wird (§152).”

17. “Nachdem ich auch im vorhergehenden deutlich erwiesen, daß der innere Zustand eines jeden einfachen Dinges sich auf alle das übrige beziehet, was in der Welt ist (§596) und der Herr von Leibniz solches dahin erkläret, daß in einem jeden einfachen Dinge die gantze Welt vorgestellet wird nach dem Puncte, wo es ist (§599), so versteht man nun auch ferner, wie alle Dinge in der Welt bis auf das kleineste mit einander seiner Meinung nach zusammen stimmen, und was er demnach mit seiner allgemeinen Harmonie der Dinge haben will, die, wie alle das übrige, was er in dieser Materie vorgebracht, vielen als ein Rätsel geschienen, welche sie sich nicht aufzulösen getrauet, indem er es weder genugsam erkläret, noch erwiesen. Jedoch, da wir zur Zeit noch nicht feste setzen wollen, worinnen eigentlich dieses bestehe, daß der innere Zustand der einfachen Dinge sich auf alles in der Welt beziehet; so lassen wir auch für jetzt noch ausgesetzt, worinnen die allgemeine Harmonie der Dinge bestehe, und ist uns genug, daß wir erwiesen, sie sey vorhanden, und daß sie sich nach dem Sinne des Herrn von Leibniz auf eine verständliche Art erklären lasse.”

18. I suspect that Wolff’s reluctance is at least in part due to the fact that Locke’s suggestion that matter might be able to think did not encounter a positive reception. Granted, Wolff need not be claiming that matter can think, but rather only that the simple elements that underly matter can think, but even this weaker doctrine may have appeared too susceptible to the charge of materialism.

19. Fabian (1925, p. 40) suggests just such a position. However, his twofold argument is rather weak. First, he presents Wolff’s reservations about the universality of representational force, but causation amongst non-representational simple beings in no way follows immediately from such reservations. Second, he cites a passage from Wolff’s Cosmologia Generalis in which Wolff says: “elementa rerum a se invicem patiuntur.” However, such a statement stands in need of considerable further explanation and, given that Wolff has important general objections to Physical Influx, it is not likely that Wolff understood such a view to entail Physical Influx.

20. Granted, Leibniz does sometimes suggest that it is “merely possible” and “just an hypothesis,” but in other passages (e.g., in those in which he raises objections to Physical Influx and Occasionalism) he clearly suggests that Pre-established Harmony alone is tenable.

21. Wolff ([1719–20] 1983, p. vii): “Ich hatte mir zwar anfangs vorgenommen die Frage von der Gemeinschaft des Leibes mit der Seele und der Seele mit dem Leibe ganz unentschieden zu lassen.”

22. “gar nichts daran gelegen ist, daß man dieses Systemata für wahrscheinlicher als ein anderes hält.”

23. It has been suggested that this fact alone contributed significantly to the hostility of some members of the theology faculty in Halle towards Wolff.

24. It should be noted that Leibniz and Wolff had little philosophical competition. Insofar as philosophy was established in the universities, it tended to be a dry and lifeless interpretation of Aristoteleanism.

25. For a lengthier description of Wolff’s rise in academia, see Wundt (1945, pp. 199–230).

26. Two volumes might seem prolix, but compared to Wolff’s six-volume German series and his considerably longer Latin reworking of the German series, Thümmig’s accomplishment should not be underestimated.

27. “Quia systemata influxus physici & adsistentiae ordini naturae adversantur (§§244, 250), atque systema harmoniae praestabilitae solum eidem sit conforme, cum ad commercium inter mentem & corpus explicandum non utatur, nisi quae essentiae & naturae mentis atque corporis conveniunt.”

28. “Cum enim nullum systema rigorosa nitatur demonstratione, nobis erit perinde, sive aliquis, prout hoc vel istud systema probabilius visum fuerit, Influxistarum, sive Occasionalistarum, sive denique Harmonistarum partibus accedere, sive nullas tueri velit.”

29. For a more detailed account of Bilfinger’s views, see Kintrup (1974) and Liebing (1961).

30. Bilfinger ([1723] 1984, p. 5): “Illud saltim hic monendus es, me non de omni harmonia praestabilita, qualem Leibnitius asseruit, in hisce paginis acturum esse: sed de harmonia solum animi atque corporis praestabilita.” For a discussion of this issue in Leibniz, see Miller (1988) and Brown (1992).

31. In 1725 Bilfinger published a more general metaphysics textbook, Dilucidationes philosophicae de Deo, anima humana, mundo, et generalibus rerum affectionibus, in which he continued to maintain Pre-established Harmony. The most significant difference between the dissertation and this textbook is that in the latter, Bilfinger, like Wolff, clearly asserts that perception need not be attributed to all of the simple elements.

32. For more details of this dispute, see Hinrichs (1971, pp. 352–87).

33. Georg Volckmar Hartmann ([1737] 1973, p. 849) notes “So wurde, nachdem der Hr. R. R. Wolff am 12. Julii 1721 in einer öffentlichen Rede die Gleichheit seiner Lehr-Sätze mit der Sinesischen Philosophie gezeigt hatte, des Tages darauf so gleich öffentlich wieder ihn gepredigt.”

34. The story here is even more complicated. Due to the question of censureship, the publication of the speech was not a straightforward matter. It was first published without Wolff’s knowledge by Jesuits in Rome, and later in various versions by Wolff and by Lange. For the complete history on the relationship between Lange and Wolff regarding merely the publication of this speech, see Albrecht (1983, pp. xc-ci).

35. Bruno Bianco (1989, p. 112), too, notes that Wolff has no right on the basis of his own behavior to be described as a hero or a martyr, as Zeller describes him.

36. Apparently, Strähler’s mistake was to attack Wolff by name.

37. The full title is: Sicheres Mittel wieder unbegründete Verleumdungen, wie denselben am best abzuhelfen. For a reprint of Wolff’s Sicheres Mittel, see Wolff ([1723a] 1981).

38. The full title is: Anmerckungen uber des Herrn Hoff-Raths und Professor Christian Wolffens Metaphysicam von denen darinnen befindlichen so genannten der Natürlichen und geoffenbarten Religion und Moralität entgegen stehenden Lehren.

39. The full title is: De differentia nexus rerum sapienties et fatalis necessitatis, nec non systematis harmoniae praestabilitae et hypothesium Spinozae luculenta commentatio. For a reprint of this work, see Wolff ([1723b] 1983).

40. The full title is: Modesta disquisitio novi philosophiae systematis de De, mundo et homine et praesertim de harmonia commercii inter animam et corpus praestabilita. For a reprint of this work, see Wolff ([1724d] 1986).

41. The full title is: Monitum ad commentationem luculentam de differentia nexus rerum sapientis et fatalis necessitatis quo nonulla sublima metaphysica ac theologiae naturalis capita illustratur, autore Christiano Wolfio. Also reprinted in Wolff ([1723c] 1983).

42. The full title is: Placidae vindiciae modestae disquisitionis de systemate philosophiae novo. Again, Lange’s work is reprinted in Wolff ([1724d] 1986).

43. For the full story, see Wolff’s Eigene Lebensbeschreibung, p. 28; Wundt (1945, pp. 230–64); Zeller (1862, pp. 47–72).

44. Thümmig and other Wolffians were also removed from their teaching posts. For example, Fischer in Königsberg was removed on the same day that Wolff and Thümmig were.

45. Wundt (1945, p. 243) expresses the following evaluation of Budde: “Budde hat seinem Ruhm als Philosophen mit demselben [Bedencken] zweifellos nicht genützt.” And Hartmann, with less distance between himself and the events, remarks (p. 877): “Aus der Vorrede . . . erkennet man sogleich, welches Geistes Kind er sey, und wie übel er auf die Wolffische Philosophie zu sprechen, und wie er über den Fall des Hrn. R. R Wolffs frohlocket.”

46. For a reprint of this work, see Wolff ([1724a] 1980).

47. In typical Wolffian style, the commentary was much longer than Budde’s original attack. For a reprint of this work, see Wolff ([1724a] 1980).

48. The full title is: Bescheidene Antwort auf Herrn Christian Wolffens Anmerckungen über das Buddeischen Bedencken Dessen Philosophie betreffendt, Welches selbst wieder beygefügt worden. For a reprint of this work, see Wolff ([1725] 1980).

49. The full title is: Nöthige Zugabe zu den Anmerkungen über Herrn D. Buddeus Bedenken von der Wolffischen Philosophie. For a reprint of this work, see Wolff ([1724b] 1981).

50. The full title is: der vernünfftigen Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen Überhaupt, Anderer Theil, Bestehend in Ausführlichen Anmerckungen.

51. The full title is: Bescheidener Beweiß, daß das Buddeische Bedencken noch fest stehe, wieder Hrn. Christian Wolffens nöthige Zugabe aufgesetzt. For a reprint of this work, see Wolff ([1725] 1980).

52. The full title is: Klarer Beweis, daß der Herr D. Budde die von ihm gemachten Vorwürffe einräumen und gestehen muß, er habe aus Übereilung die ungegründete Auflagen der Hällischen Widersacher recht gesprochen. For a reprint of this work, see Wolff ([1725] 1980).

53. The full titles are: 1) Ausführliche Recension der wider die Wolfianische Metaphysic auf 9. Universitäten und anderwärtig edirten sämmtlichen 26. Schriften mit dem Erweise, daß der Herr Professor in seinen versuchten Verantwortungen bisher keineswegs gerettet habe noch auch künftig retten kann: denen zum besten, welche besagte Schriften weder alle haben noch alle lesen können; doch aber von gedachter Philosophie gern urtheilen wollen oder auch davon ohne sie recht eingesehen zu haben eingenommen sind; 2) Nova Anatome seu idea analytica Systematis metaphysici Wolffiani, qua illud in integra compage sua, secundum suam sic dicti Idealismi & Materialismi genesin, seu compositionem biformem ob graves rationes denuo resolutum atque exvisceratum exhibetur: Cui e speciali consilio & consensu ordinis Theologici in Academ. Frideric. praemittitur oratio de sappientia Sinarum Confuciana, quam Systematis istius Autor Halae Saxonum die XII Jul. An. 1721.; and 3) Ausführliche Nachricht von seinen eigenen Schriften, die er in deutscher Sprache herausgegeben, respectively. For a reprint of this final work, see Wolff ([1726] 1973).

54. See Fabian (1925) for a brief description of some of the more minor figures. I should note that even Fabian’s account is not exhaustive.

55. “Wie nun im verwichenem Jahre die Wolffische Welt-Weisheit hefftig war bestritten worden; So fuhre man auch darmit in diesem 1725. Jahre mit gleicher Eiffer fort, welches man aus denen heraus gekommenen Streitschriften hinlänglich sehen kan, deren Verzeichniß wir anjetzo mittheilen wollen.”

56. “Auch in diesem 1726 Jahre hatte man noch nicht aufgehöret, noch nachgelassen, die Wolffische Welt-Weißheit zu wiederlegen, wie wir solches aus denen nachfolgenden Schrifften ersehen können.”

57. The full title of Rüdiger’s treatise is: Herrn Christian Wolffens, Hochfürstl. Heßischen Hoff-Raths und Prof. Philos. & Mathem. Primarii &c. Meinung von dem Wesen der Seele und eines Geistes überhaupt und D. Andreas Rüdigers, hochfürstl. Sächsischen wircklichen Raths und Leib-Medici in Forst, Gegenmeinung.

58. “Nunmehro fieng es an in diesem Jahre etwas ruhiger zu werden. Denn obschon die Langische Parthey wohl durch verschiedene Recruten sich noch täglich mehrete und zunahm, auch die alten ihre angefangenen Streitigkeiten fortsetzten; So verspührten sie doch nunmehro einen starcken Mangel an hinlänglicher Munition”. Hartmann also tells a nice story about how Lange still tries to win the war. “Weil er [i.e., Lange] aber Herrn R. R. Wolffen aus seinen Posten nicht wieder vertreiben kunte; so versuchte er ihn durch Königl. Preussische Mandata, mit seiner Philosophie aus der Christenheit zu verjagen, wodurch bey ernster und schwerer Straffe durch das ganze Preussische- und Thur-Brandenburgische Land verboten wurde, weder des Hrn. R. R. Wolffens Metaphysic und Moral, in selbigen zu verkaufen, noch auf Universitaeten drüber zu lesen” ([1737] 1973, p. 928).

59. It is worth pointing out that similar charges are raised against Lessing in the Pantheismusstreit later in the eighteenth century.

60. Bruno Bianco (1989, p. 113) suggests: “[daß] diese Argumente keine bloß vom Gefühl bedingten Stegreifargumente sind. Als ausgearbeiteter Ausdruck bestimmter philosophisch-religiöser Traditionen decken sie einige grundlegende Aporien des großartigen Leibniz-Wolffschen Gedankenbaues auf und nehmen einen beträchtlichen Einfluß auf die deutsche Aufklärungsphilosophie bis hin zu Kant.” (these arguments are not made merely off the cuff and conditioned by sentiment. As a worked out expression of certain philosophical-religious traditions they reveal several basic aporia of the Leibnizian-Wolffian conceptual scheme and exercise a considerable influence on German philosophy of the Enlightenment up through Kant.)

61. I should note that Wolff does not use the term “restitution miracle”. It is also worth noting that a similar objection has been raised by Kulstad (1993).

62. Wolff is not always as careful as he should be about the distinction between the nature of a simple thing and its complete concept or essence. Leibniz defines a miracle as an event that cannot be explained by the nature of a thing, but it can be explained by that thing’s complete concept. Wolff, however, defines ([1719–20] 1983, p. 386) a miracle as an event that surpasses nature and cannot be explained through the essence of things and their force.

63. This feature is somewhat more understandable because Lange misrepresents Wolff’s position so often.

64. Unfortunately, Wolff does not take Lange’s criticism as an opportunity to clarify what is a serious philosophical issue, namely, clarifying the nature of the basic faculty of the soul and exactly how it relates to the two main derivative faculties that human beings do have (the understanding and the will).

65. “Wenn die Vereinigung zwischen Leib und Seel nicht physisch, oder natürlich, sondern nur metaphysisch ist, und in einer Ubereinstimmung der Handlungen besteht: so kan ein philosophus dieses systematis dem Leibe nach in Europa, insonderheit in Teutschland zu Halle, der Seelen nach aber in Africa unter den Hottentotten seyn; und zwar in solcher Ubereinstimmung der Handlungen, daß, wenn die Seele in Africa gedencket, daß sich der Leib so und so bewege, der Leib in Europa sich bloß vermöge seiner Structur und der umstehenden Cörper ebenalso beweget.”

66. Cf. Ariew and Garber (1989, pp. 196–97) for Leibniz’s response.

67. Wolff ([1724a] 1980, p. 79): “Wo habe ich aber gelehret daß im Leibe Bewegungen erfolgten ohne daß die Seele dieselbe freywillig wollte.”

68. He also claims that Pre-established Harmony is the foundation of Wolff’s entire philosophy, a point that infuriated Wolff, since he was explicit already in the Vernünfftige Gedancken and also in various later passages that Pre-established Harmony is not fundamental to his system.

69. “Dieses kan unmöglich bestehen wenn gleich wahr wäre daß diese Welt nothwendig existiren müste und schlechterdinges unmöglich wäre daß eine andere existiren känte. Denn dadurch daß GOtt diese Welt für allen andern hätte nothwendig hervor bringen müssen und in der Wahl keine Freyheit gehabt würde in ihrer Beschaffenheit nichts geändert. Die Welt bleibet einmahl wie das andere ich mag setzen Gott habe sie freywillig oder nothwendig erwehlet. Die Wahl ändert nichts in der Sache.”

70. See Wolff ([1719–20] 1983, pp. 314–17).

71. “Ohne die Zufälligkeit der Welt kan im Systemate harmonia praestabilitae die Freyheit nicht bestehen.”

72. For a more complete biography of Andreas Rüdiger, see Wundt (1945, pp. 82–98) as well as Stolle (1736, pp. 474–77).

73. For references I shall give both Rüdiger’s annotation (which consists of a letter and then a number, whereby the sequence runs through each letter of the alphabet before proceeding to the next number) and the page number, except for the preface which is not paginated, in which case I will give the § number.

74. “nicht allein nicht verstehen kan, wie Leib und Seele in einander wircken, sondern man begreift auch, daß es unmöglich sey, daß sie in einander wircken können.”

75. Rüdiger then notes that he will not presuppose his own account of the soul in order to criticize Wolff, since “most learned people cannot yet hear the word ‘matter’ spoken of the soul” (§14): “Weil doch aber die meisten Gelehrten das Wort Materie von der Seele noch nicht hören können, so wil ich mich desselben in dieser Widerlegung gäntzlich enthalten, und meinen Gegenbeweis aus anderen Gründen hernehmen.”

76. “Ist sie nun nicht materialis, so ist in ihrer gantzen Substanz kein punctum physicum, ist dieses nicht da, so kan sie weder berühren noch berühret werden: denn dieses ist ein Postulatum, daß aller attactus in puncto physico geschehen muß. Kan nun die Seele weder berühren noch berühret werden, so kan sie auch weder in den Leib agiren, noch der Leib in sie: denn es ist gleichfals ein Postulatum, daß keine actio in aliud ohne Berührung geschehen könne.”

77. “Denn wenn eine geschaffene Substanz wäre, die nicht extensa wäre, so hätte sie nicht partes extra partes: hätte sie nicht partes extra partes, so hätte sie keinen Fördert- und Hintertheil, hätte sie keinen Förder- und Hintertheil, so hätte sie keinen Anfang und kein Ende, und wäre doch nicht Gott, so könte man ein erschaffen Wesen nicht dencken, könnte man es nicht dencken, so wäre es entweder nichts, oder es gehörete doch ad incognitum. Also wird nun non-extensum entweder negative genommen, so heist es gar nichts, oder positive, so heist es etwas, davon wir nichts wissen.”

78. It is not obvious that Rüdiger is not using extension equivocally in the argument, sometimes meaning ‘created’, other times meaning ‘spatial’.

79. “Die Partes integrantes sind keine verae partes, sondern die Essentiales und andere als Organicae und Mechanicae. §23. Denn das sind keine verae partes in rebus naturalibus die nicht die Grentzen ihrer extension von GOtt oder der Natur, nemlich ihrer beywohnenden Kraft, haben; die partes integrantes aber haben die Grentzen ihrer Extension von dem arbitrio der Menschen: welches daraus erhellet, daß nachdem es dem Menschen beliebet, so ist ein pars integrans hundert tausendmal grösser, und hundert tausendmal kleiner, ohne daß GOtt oder die Natur zu dieser Begrentzung etwas beytrage: so ist demnach der pars integrans ein Menschen-Werck, und nicht ein Werck GOttes und der Natur. Hingegen die partes essentiales, als die Elementa, und der Spiritus, haben nicht allein ihre Kraft von GOtt, sondern auch die Grentzen ihrer Extension, und wenn sie solche vergrössern oder verkleinern, so geschieht solches durch die ihnen von GOtt mitgetheilte Kraft der Bewegung, das ist durch ihre Natur, daß also besagte Grenzen allezeit ein Werck GOttes sind, oder der Natur, und von keinen arbitrio der Menschen dependiren.”

80. “Wenn man also sagt, die Seele, nemlich das Subjectum derselben, sey materiale, und dahero zulässet, daß von ihrer Substanz partes integrantes können gesagt werden, so folgt daraus nicht, daß sie ein zusammengesetztes, sondern nur, daß sie ein von GOtt erschaffenes Wesen sey, das anders als durch den Willen und Allmacht desjenigen, der es erschaffen, nicht wiedrum vergehen kan. Hingegen würde sie ein wahrhaftig zusammengesetztes Wesen, und das auch, wegen seiner innerlichen Beschaffenheit, wiedrum vergehen könte, seyn, wenn man sagte, daß sie aus partibus essentialibus, z.E. aus den Elementen bestünde.”

81. “Ich halte also zwar das Subjectum der Seele pro materiali, die Seele selbst aber, so ferne sie pro forma corporis genommen wird, halte ich mit denen übrigen Philosophis und Theologis pro immateriali . . . Jedoch ist das Subjectum der Seele deßwegen nicht pro compositio zu achten, sondern es ist und bleibet substantia simplicissima, weil die partes integrantes, dadurch es muß begriffen werden, keine wahrhafte, sondern nur eingebildete partes sind.”

82. “Die Seele selbst, das ist, in Abstracto genommen, ist deswegen immaterialis, weil sie etwas Göttliches ist.”

83. “einen Unterschied zwischen einem Subjecto, und der Kraft eines subjecti.

84. “(1) daß ein Subjectum immateriale auf keine Art und Weise begriffen werden kan, eine immaterielle Kraft aber, einiger massen. Nemlich eine Kraft bedeutet ein Vermögen der Bewegung; ob man nun zwar besagtes Vermögen nicht dencken kan, so kan man doch die Bewegung begreiffen . . . Mit dem Subjecto verhält es sich ganz anders. Denn es ist von Natur ein ausgedehntes Wesen, und das, ut tale, keine Kraft der Bewegung hat: Darum, wenn man bey demselben keine Extension dencken darf, so ist nichts mehr übrig, daß man gedencken oder begreiffen könne.”

85. “Denn ein jedes wahrhafftiges Ding ist entweder eine Substanz, oder ein Accidens: Des Hn. A. einfache Dinge können keine accidentia seyn, denn sie sollen Kräffte haben §.115. also müssen sie Subjecta oder Substanzen seyn: sie können aber auch nicht Substanzen seyn, weil alle Substanzen ohne Figur und Grösse, ich will nicht sagen, nicht seyn, sondern auch nicht einmal gedacht werden können.”

86. “Da die Seele ein einfaches Wesen ist, §.742. ein einfaches Ding, oder Wesen, keine innerliche Bewegung hat, §.81. so begreife ich nicht, wie die Seele eine Krafft habe. Denn posito, daß eine Krafft ein Ansatz einer innerlichen Bewegung sey, ein solcher Ansatz, oder Krafft, aber ist vergeblich, wenn er nicht zur Wircklichkeit gereichet, weil nun GOtt und die Natur nichts vergeblich machen, so ist in der Seele auch, wenigstens bißweilen, eine wirckliche innerliche Bewegung, welches doch der Hr. A von den einfachen Dingen, oder Monaden §.81 ausdrücklich verneinet.”

87. “Man unterscheide nur verschieden Kräffte, und entgegengesetzte, oder contraire. Das Exempel, das der Hr. A. angiebt, ist von contrairen Kräfften, und beweiset vor ihn nichts, weil er nur erweisen will, daß ein einfaches Ding nicht verschiedene Kräffte haben könne.”

88. The issue here is that even if one were to grant Wolff that all faculties can be derived from a single faculty, one could object that the faculty of representation could be the single requisite faculty.

89. “Denn ich sage es frey, daß ich mit denen andern, die sich der hypothesi de harmonia praestabilita widersetzt haben, hierinnen einerley Meynung habe, daß nemlich gedachte hypothesis libertatem voluntatis humanae aufhebe, folglich auch den Grund der Theologie, Morale und Politique.”

90. “ich und diejenigen, die meine wenige Lehren annehmen, wir können es nicht allein gar wohl begreiffen, sondern auch auf eine weit verständlichere Art, als der Hr. A. seine harmoniam praestabilitam, erklären.”

91. “so möchte ich den zureichenden Grund wissen, warum die Seele . . . nicht . . . durch die poros des Leibes ausziehet, und sich ausser denselben mit Vorstellungen der gantzen Welt belustigt.”

92. “Denn Leib und Seele bewegen sich nicht als Machinen.”

93. “Daß eine Krafft, die sich nach etwas richtet, sich in allen ihren Wirckungen darnach richte.”

94. In other passages, Rüdiger repeatedly charges that there is no reason, according to Pre-established Harmony, why the soul should be limited by the body. See Rüdiger (1727, z4, pp. 77–79); (k5, pp. 91–92); (n5, p. 95).

95. Both Gottsched and Knutzen will later raise objections to Pre-established Harmony that are based on similar considerations.

96. Rüdiger (1727, p5, pp. 99–100): “Diese Erkäntniß ist Paralogistisch. Denn der modus zu schließen ist entweder eine argumentatio a particulari ad universale, also: Weil einige mit Gliedmaßen der Sinnen begabte Cörper Seelen haben, die sich die Welt vorstellen, Ergo haben alle solche Cörper solche Seelen, und also auch die Thiere; oder es ist ein paralogismus simulitudinis folgendes Inhalts: Die Thiere sind dem Menschen darinnen gleich, daß sie Gliedmaßen der Sinnen haben, darum sind sie ihm auch darinnen gleich, daß sie eine Seele haben, die sich die Welt vorstellen kan. Daß diese Art zu schließen nichts taugt, ist daraus klar, weil man auf eben diese Art, einen gantz falschen Schluß inferiren kan, nemlich: Darum sind sie ihm auch darinnen gleich, daß sie Vernunft und Freyheit haben. Unterdessen ist gewiß, daß man von den organis sensuum, auf die Beywohnung der Seele schliessen kan, nach einer Art der Probabilität, die ich im Sens. V. & F. Lib. III. Cap. VII kat anqrwpon genennet, nemlich folgender maßen: Die Thiere haben organa sensuum, niemand kan sagen, qozu diese organa nütze wären, wenn sie nicht einer Seele zum Gebrauch dienen sollten, darum muß eine Seele in den organischen Leibern seyn. Allein dem Hr. A. vergönnet sein praejudicium nicht, also zu schliessen, denn er hat sich einmal eingebildet, daß die Seele alle das Ihrige, ohne Beyhülfe des Leibes, und dieser gleichfals alles, ohne Beystand der Seele, thun könne. Also könnnen wir nun zwar, die wir den Influxum statuiren, wissen, daß die Thiere eine Seele haben, aber der Hr. A. kan davon keine Versicherung haben, vielmehr hätte er glauben sollen, daß die Thiere gar keine Seelen hätten. Denn weil er sich einmal im Sinne gefaßt, daß der menschliche Leib alles ohne einzigen Beytrag der Seele, so far auch syllogismos, machen könte, so muß er auch sagen, daß der Thierische keine Seele brauche zu seinem Thun. Daß wir Menschen nicht blosse Leiber sind, wissen wir, nach des Hrn. A. Meynung daher, weil wir uns bewust sind; aber wer sagt uns, daß die Thiere sich bewußt sind? da nun der Hr. A. dieses nicht weiß, so kan er mit dem mindesten Grunde nicht sagen, daß die Thiere Seelen haben, geschweige dann Seelen mit einer vorstellenden Krafft. Wir aber, die wir den Influxum statuiren, können es genau darthun.”

97. “1) Wie die Seele als ein immaterielles Wesen, nach Art einer cörperlichen Machine Gedancken hervorbringen könne. 2) Wie der Leib, z. E. die schwache Bewegung des Lichts, vermittelst seines Mauls nicht allein Wörter, sonder sogar auch, ohne einzige Mitwirckung der Seele, bloss mechanice, gantze sollogysmos . . . hersagen könne.”

98. “Denn wer wissen will, was unmöglich ist, der muß alle Kräfte der Natur, samt ihrer Quantität, (das ist nicht nur metaphysice, sondern auch disciplinaliter) wissen, wer dieses weiß, ist allwissend.”

99. “Der Hr. A. spielet immer mit der Dreydeutigkeit des Wortes Grund. Denn wir nennen einen Grund überhaupt alles, was zu des andern Hervorbringung etwas beyträgt, es mag 1) seyn die Absicht eines vernünftigen Wesens, oder 2) eine causa physica ohne Vernunft, oder 3) eine causa pure mechanica. Wenn nun der Hr. A. sagt, die Bewegungs-Gründe machen eine Handlung nicht nothwendig, sondern nur gewiß, so gebe ich es zu von der ersten Art, nemlich, wo sie Absichten eines vernünftigen Wesens sind: keinesweges aber von den Bewegungs-Gründen der andern und dritten Art, als welche beyde nothwendige Handlungen (oder besser zu reden Bewegungen) hervorbringen. Da nun die Bewegungs-Gründe der Seele, nach dem concept des Hrn. A. zu der dritten Art gehören, so können die Handlungen derselben auch nicht anders als gezwungen, und nothwendig seyn.”

100. For information on Hollmann as the first professor in philosophy at the University of Göttingen, see Cramer (1988, pp. 101–43).

101. Hollmann (1724a, p. 76): “unde diversissima illae, nulloque modo saepius cohaerentes in anima perceptiones oriantur, aut quid sit, quod animam ita determinet, ut ab hac perceptione ad illam, cui cum priori nihil plane commune est, cum adfinitas alias, cum prioribus magis cohaerentes, posset, naturae veluti quadam necessitate abripiatur.”

102.unde fiat, quod anima quascunque, etiam subitaneas, corporis, imprimis cerebri, mutationes exacte sequatur.

103. Hollmann (1724a, p. 91): “quod perceptiones atque sensationes non continua serie atque ordine nunquam interrupto fiunt, sed infinitis fere cogitationibus, creberrime de variis rebus susceptis, singulis fere momentis, interturbantur.

104. Hollmann (1724a, p. 92): “quod, si omnes perceptiones affinitatis rationem inter se servarent, secuturum necessario esset, ut, quotiescunque eadem numero res, quarum perceptiones ante aliquod tempus abuimus, ab anima nostra iterum repraesentarentur, eadem etiam sensationes, qua tum temporis hasce perceptiones vel comitatae, vel insecurae fuerunt, eodem etiam ordine denuo easdem consequerentur, adeo, ut ne minimum quidem discriminis observare inter illas liceret.”

105. Hollmann (1724a, p. 93): “quod, si eo modo, quemadmodum a defensoribus harmoniae praestabilitae explicantur, animae perceptiones fierent, nullum anima discrimen facere posset inter novam percepionem rei jam antea aliquando perceptae & ejusdem reminiscentiam, sive repraesentationem, a sola memoria vel phantasia, citra objecti externi praesentiam, factam.”

106. Hollmann (1724a, p. 99): “quod motus corporis nostri saepius fiunt, quando nullae sensationes, hoc est, nulli spirituum animalium motus in organis sensuum facti, praecesserunt.

107. Hollmann (1724a, p. 101): “Quodsi enim corpus nostrum non nisi ab aliis corporibus, in sensuum organa agentibus, moveretur, fieri aliter non posset, quam ut iisdem manentibus objectis, iidem semper contingerent motus, siquidem alias, si contrarium his eveniret, diversi ex una eademque causa sequerentur effectus, quod tamen nec per principia celeb. Wolffii concedi, nec per rei naturam fieri, potest.”

109. Hollmann (1728, p. 23): “Oportere illa, inter quae dari aliqua debet proportio, in aliquo convenire tertio, atque eatenus esse homogenea, non nego: si enim omnis deficeret similitudo, nulla posset dari proportio; in omni autem eadem convenire debere, quo sensu homogenea a TE videntur accipi, nondum apparent, cur affirmemus, siquidem ubivis exempla obvia sunt, ubi heterogenea quoque, dummodo in aliquo tertio inter se conveniant, proportionem quandam inter se admittunt.” Unfortunately, Hollmann does not suggest what that third thing would be, though one can surmise that it might be God or the conception of a substance in general.

110. “convictum me ergo esse fateor, quod, illa argumenta, quae duabus olim Dissertationibus adversus Harmoniae Praestabilitae systema attuli, ut & dubia illa, qua in Dissertatione Epistolica, ad Te data, adhuc residua videbantur esse, nequaquam adversus illud ipsum systema praevaleant, nedum Physicam ejusdem impossibilitatem, quod antea persuasus eram, ostendant.”

111. “secundum systema influxus vero facilius concipi omnia possunt. Ratio enim sufficiens idearum non est in anima, sed in influxu idearum sensualim in animam, hae vero ipsae rationem suam sufficientem habent in corporibus, extra nos existentibus, eorundemque varia modificatione, varioque ad sensus appulsu.”

112. For a more detailed account of Gottsched’s contribution to the debate about Pre-established Harmony and Physical Influx, see Watkins (1995a).

113. It is unclear whether these objections were actually made by any Cartesians in this form against Physical Influx, since Gottsched provides citations only from Descartes’s Principia philosophiae.

114. “Quicquid clare & distincte sine alio quodam ente intelligi potest, illud sine illo ente exsistere potest. a) Atqui mentem clare & distincte sine facultate motrice concipere possum.”

115. “Das Wort Einfluß wird zwar in metaphorischem oder verblümtem Verstande genommen.” (Except when explicitly noted all of the quotations from the seventh edition were present in the first edition.)

116. This argument has certain affinities with Rüdiger’s.

117. “Keine derselben ist noch vollkommen erkläret oder demonstriret; eine jede davon hat noch ihre Schwierigkeiten: es kann sich also ein jeder and diejenige halten, die ihm am besten gefällt. Mir ist es indessen allezeit vorgekommen: daß man nicht eher Ursache habe, die allerälteste und gemeineste Meynung vom natürlichen Einflusse zu verwerfen; bis man sie vollkommen widerleget, und ihre Unmöglichkeit erwiesen haben wird. Dieses aber ist, noch zur Zeit, von niemanden geschehen.”

118. “Doch ich gebe dieses alles nur für bloße Muthmaßungen aus, und lasse es dahin gestellt sein: welche Meynung bey einem reifern Erkenntnisse der Seele und des Leibes, mit der Zeit die Oberhand behalten wird.”

119. In a way, the status of Gottsched’s position is very much like that of Thümmig’s. Both have definite views about which system should be preferred, but neither one wants to present the system they prefer as conclusively established. (The difference between the two is of course that Thümmig’s private view was to accept Pre-established Harmony, whereas Gottsched has already shifted away from it towards Physical Influx.)

120. For the best account of Knutzen’s general significance, see Erdmann (1876).

121. For a more detailed discussion of Knutzen’s arguments for and defense of Physical Influx, see Watkins (1995a).

122.§. XXVIII. Vis seipsam mouendi inuoluit vim alia quoque mouendi realiter.

Vis mouendi, quae efficit, vt ens quodpiam locum suum proprium mutet, sine vi mouendi, res alias, quibus cingitur, concipi nequit, sed ista posita haec simul ponatur, necesse est. Vis enim mouendi, quae efficit, vt ens locum suum proprium mutet, non est, nisi conatus, hunc suum mutandi locum (§. 24.) i. e. occupandi locum ab eo, quem iam occupat, diuersum et quidem eidem continuum (§. cit.). Sed coexistentia alia, quae vbique mobile cingunt, loca ista a loco mobilis diuersa obtinent; duo autem diuersa entia simul in eodem loco esse nequeunt (§. 23.): ens ergo vi se ipsum mouendi praeditum, res alias loco pellere nitetur, si illae resistant. Quod si vero etiam sponte cedere supponantur, tamen id quod in nisu tali, qui requiritur ad motum extra se perficiendum, siue alias res loco pellendas, in motu progressiuo iam adest; cum resistentia sit tantum causa occasionalis motus, nec vi intrinsecae quicquam addat: Ens ergo, quod se ipsum mouet, conatu gaudet mutandi locum coexistentium seu vi mouendi res alias (§. 24.). Vis ergo, se ipsum mouendi, sine vi mouendi res alias concipi nequit, sed ista posita, haec ponitur simul.”

123. Note that Knutzen formulates this argument quite generally so as to pertain to any being of which a Leibnizian will claim that it can change its own place. Thus, the argument will certainly apply to bodies, to corporeal substances of Leibniz’s middle period, and perhaps even the monads of the later Leibniz (since monads are in some sense in a place and responsible for the changes that occur in bodies so that one could say that they change the place of their body). For a discussion of Leibniz’s conception of substance in his middle and later periods, see Sleigh (1990), Mercer and Sleigh (1994), and Rutherford (1994).

124. As the argument stands, it is, of course, unsound. For Knutzen provides no reason for thinking that every being is surrounded in all directions. Accordingly, the argument would require substantial supplementation in order to appear plausible. However, Leibniz cannot lodge this objection, because he accepts the Principle of Sufficient Reason which excludes the possibility of a void. (Cf. Primary Truths, Leibniz 1989, p. 33.) Leibniz has additional reasons for rejecting the void. Cf. Specimen dynamicum in Leibniz (1989, p. 130).

125.Idem quoque aliter posset demonstrari: Simplicia elementaria sunt impenetrabilia, ex sententia Leibnitii, qui substantiae finitas omnes impenetrabiles asserit. Videatur eius Epistl. ad C. Wagnerum p. 201. Tom. I. Epistl. Edit. Kortholtianae. Hinc fieri non potest, vt vna sit in loco alterius. Ergo datur aliquid reale, vi cuius vnum simplex aliud excludit ac contra nititur, ne in suum irruat locum. Cum enim moueri simplicia certissimum sit (§. 27.) neque diuersa simplicia secundum contrariam directionis lineam moueri, adeoque sibi inuicem occurrere impossibile sit, imo etiam id quod ex conflictu corporum et occursu eorundem colligimus, reuera contraria directione contra se inuicem ferantur; sequitur in eo casu statuendum, aut simplicia se inuicem penetrare, quod contra asserta Leibnitii; aut si inuicem resistant; in se inuicem agere. Q. e. d.”

126.Dum corpus in mentem agit vi systematis physici influxus, neque menti rerum externarum ideas infundit, neque vim repraesentatricem; sed modo vim mentis eiusdemque substantiam tali ratione modificat, ut repraesentatio in mente oriatur. Mens vero, dum in corpus agit, nullam eidem vim motricem infundit; sed eam tantum, quae corporis elementis inest, ita actione sua modificat ac dirigit, ut motus demum in corpore producatur. Ideae enim ac vis repraesentatrix vel accidentia sunt vel substantiae. Si sunt accidential: menti a corpore infundi ac locali quodam motu e corpore in mentem transire nequeunt; accidentia enim e subiecto non migrant in subiectum (§. 791. Ontol.). Si vero substantias esse supponas: similiter eiusmodi transitus concedi nequit, cum mens sit substantia simplex (§. 18.), talis vero substantia alterius vel plurimarum aliarum substantiarum receptaculum esse nequeat. Ergo neque ideae, neque vis representatrix e corpore in mentem transfundi possunt. Cum tamen per corporis actionem repraesentationes rerum externarum in mente prodeant (§. 40. not.): nil superest, quam ut corpus, dum in mentem agit, vim eius ac substantiam ita modificet, vt repraesentationes rerum externarum in mente reuera prodeant seu excitentur. Simili ratione evinci potest, quod nulla vis motrix ex mente transeat in corpus: adeoque mentis actione eae tantummodo vires, quas eiusdem elementis inesse demonstrarunt recentiores (§. 196. Cosmol.), certa ratione modificentur ac dirigantur, vt sic demum harum virium determinatione determinatus in corpore motus producatur.”

127. “nego minorem, sc. quod ex Physico Influxu sequatur, in conflictu corporum inter se eandem virium quantitatem haud conseruari.”

128. “Adeoque quamqui nondum euictum est ac euinci potest, istam motus legem de conseruanda eadem virium viuarum quantitate non modo corporibus in se inuicem agentibus, sed et menti in corpus agenti et vicissim praescriptam esse; prorsus nil praesens objectio Influxui physico nocebit.”

129.quod sc. Corpus quodlibet perseueret in statu suo quiescendi et movendi uniformiter in directum, nisi a causa extrinseca statum suum mutare cogatur” and “Euidentissimum igitur est, mentem in statu suo acquiescendi ac mouendi uniformiter in directum, donec ab extrinseco statum mutare cogatur, haud permanere.”

130. It should be noted that Knutzen’s position here is rather ambiguous. In the first two quotations his position seems to be that the conservation law could hold for mind-body interactions (and that until it is shown that the law cannot hold for mind-body interactions, there is no objection to Physical Influx on this basis), whereas in the last quotation Knutzen seems to be denying that the law holds for mind-body interactions.

131. “nulla vis per influxum ex una substantia transfertur in alteram, sed nouae tantum limitationes ex vi substantiae propria, quae a substantia contingente excitatur modo, oritur. . . . Cum nec aliter in corporibus ille influxus sit concipiendus: utpote quorum quoque unum in alterum per actionem non transfert vim ullam.” Reusch also gives a nice explanation as to why Physical Influx is called physical (1735, p. 534): “Quum quoque ea sit ratio agendi omnium substantiarum finitarum, quae per naturam seu vim, qua constituit substantias, eidem competit: influxus ille, seu actio, substantiae in aliam substantiam dici potest physicus seu naturalis.”

132. “prorsus naturale et nullum habet incommodum.”

133. “vel nulla actio substantiae creatae unius in alteram, adeoque nec corporis in corpus sit admittenda, quod tamen adversam est dogmatibus eorum, qui reliqua asserunt systemata, vel nulla erit ratio, cur hoc systema caussalitatis in hoc commercio mentis et corporis impugnetur: nam actio corporis in corpus ultimato in actiones substantiarum simplicium seu elementorum in se invicem resoluitur.”

134. “mutationum leges in universo negligit (§796ff.), atque actionem substantiae simplicis in simplex atque compositum, et v.v, huius in illam tollit; quae tamen et fieri potest (§§576, 578, 581ff.) et necessaria est, si ulla actio creaturae in creaturam (§545ff.) ipsaque corporis existentia salua esse debeat (§572).”

135. Neither Erdmann (1876) nor Fabian (1925) suggest that Reusch is simply following Knutzen either on this specific point or in general. Despite the fact that both publish their works in 1735 (and there seems to be no way of finding out in which months each of these works appeared), Knutzen does defend his dissertation a few years before, such that it is possible that his main arguments spread by word of mouth into a wider academic community. Unfortunately, I have been able to find no further evidence in support of such a view.

136. “systemate harmoniae praestabilitae posito omnium corporum existentia videtur supervacanea, adeoque sapientiae divinae adversa, utpote quae nihil eligit frustra; nam in theologia naturali demonstratur, quod ultimus entium finitorum et creationis finis sit illustratio gloriae divinae. Quae cum obtineatur, si creaturae intellegientes pro motivis actionum suarum assumant perfectiones divinas: corpora, ceu intellectu destituta (§672), immediate gloriam Dei non promovent, sed tantum mediate, dum entibus intellectu praeditis occasionem praebent cognoscendi Numinis perfectiones. Sed in systemate harmoniae praestabilitae substantiae rationales omnem cognitionem vi sua sine corporis adjumento acquirunt et corpora habent modo rationem causae exemplaris, respectu idearum sensualium (§805ff. 292): unde, quoniam caussa exemplaris externa, seu extra ideam caussae efficientis, existit superflue seu frustra, si idea illius fuerit satis accurata (§293), nec ratio adesse videtur sufficiens, cur corpora extra intellectum Dei infallibilem existere debeant.”

137. Of course it is an oversimplification to claim that a causal condition is also a necessary condition, but the general point is nonetheless clear.

138. Not only do Knutzen and Reusch present the most compelling arguments, they are perceived as having the most compelling arguments, since i) their arguments are repeatedly discussed in the ensuing debates and ii) especially Knutzen’s work is referred to standardly.

140. Cf. for instance Johann Friedrich Bertram’s Beleuchtung der Neu-getünchten Meynung von der Harmonia Praestabilita durch Veranlassung der jüngst-edirten Reinbeckischen Erörterung or a work by an anonymous “theophili sinceri” entitled Sendschreiben an alethophilum, darin deutlich wird, daß der Herr Probst Reinbeck die Wolffische Meynung von der Harmoniae Praestabilita in der That angenommen habe, es nur nicht Wort haben wolle, as well as Acht neue merckwürdige Schriften, die in der Wolffischen Philosophie von neuem erregte Streittigkeiten betreffend, all published in 1737. For other details, cf. Fabian (1925, pp. 113–14).

141. For more on Baumgarten on this issue, cf. Ameriks (1992).

142. “substantia in substantiam extra se agens in eam influit, adeo influxus (actio transiens) est actio substantiae in substantiam extra se.”

143. “Monades huius mundi simultaneae locum, successivae sibi mutuo determinant aetatem, §281, 85 hinc in se mutuo influunt, §211, in conflictu positae, §213. Ergo est in hoc mundo influxus et conflictus universalis, §48, 306.”

144. Contrary to Erdmann’s claim (Erdmann 1876, p. 95) there is some basis in Leibniz for this kind of distinction, since Leibniz does at times allow that other substances contain the ideal ground for changes in a given substance.

145. “Si passio illius substantiae, in quam altera influit, simul est ipsius patientis actio, passio et influsux dicuntur ideales. Si vero passio non est patientis actio, passio et influxus dicuntur reales.”

146. This terminological move may be obfuscatory. The mere fact that something acts on itself does not imply that nothing else can act on it. Thus, Baumgarten’s definitions of ideal and real influx do not (or at least should not) map directly onto Pre-established Harmony and Physical Influx. Cf. my discussion of Meier below.

147. “Cum harmoniae praestabilitae universalis condicio, sive qua non, sit possibilitas eius in mundo perfectissimo, haec demonstranda est harmoniam praestabilitam demonstraturo per §462. Alias ita patet: ex quavis cuiusvis mundi monade singulae mundi, ad quem pertinet, partes cognosci possunt, §400, ergo et singulae mutationes mundanae, §354, 155. Tales autem sunt omnes passiones cuiusvis monades mundanae, quam ab alia sui mundi monade patitur, §210. Monas autem patiens est vis, §199. Ergo epsa illa monas ab alia monade mundana patiens est ratio huius passionis suae, et singularum eius partium, §354, 155, hinc ratio huius passionis sufficiens, §14, 21, adeoque data passio ipsius simul est patientis actio, §210. Ergo passiones omnes monadum cuiusvis mundi, quas ab aliis monadibus mundanis patiuntur, sunt tantum ideales, §212.”

148. “[a]lle übereinstimmende Veränderungen, der Substanzen dieser Welt, können aus andern endlichen Substanzen erkannt werden. Sie haben also ihren Grund in andern endlichen Substanzen, die außer derjenigen, deren Zustand auf eine übereinstimmige Art verändert wird, vorhanden sind §9. Diejenige Veränderung des Zustandes, die ihren Grund in einem andern Dinge hat, wird ein Leiden genennt, folglich sind alle übereinstimmige Veränderungen in dieser Welt Leiden. Diese Leiden haben ihren Grund in andern endlichen Substanzen. Alle übereinstimmige Veränderungen in der Welt sind demnach natürliche Leiden §14. Ein allgemeiner Influxionist hält alle natürliche Leiden für reelle Leiden §14. Folglich muß ein allgemeiner Influxionist, alle Veränderungen in dieser Welt, die natürlicher Weise hervorgebracht werden, für reelle Leiden halten. Keine einzige Veränderung des Zustandes kan demnach, durch die eigne Kraft der Substanz, in welcher diese Veränderung gewürckt wird, hervorgebracht werden, sie verhält sich also dabey bloß leidentlich §11. . . . Welcher Influxionist wird das wohl zugeben?”

149. Meier’s argument has serious weaknesses. The main weakness is that there seems to be no reason why real influx must be defined as it is (namely in such a way that it denies intra-substantial causation).

150. “Wenn eine endliche Substanz würckt, so wird jederzeit ihr innerer Zustand dadurch verändert. Oder: so oft eine endliche Substanz handelt, so oft wird durch diese Handlung, in ihr selbst, eine innere Bestimmung hervorgebracht, die vorher, ehe sie handelte, nicht in ihr anzutreffen war. Man nehme das Gegentheil an. Eine endliche Substanz soll würcken, aber durch diese Handlung keine Bestimmung in ihr selbst hervorbringen. Durch eine jede Handlung wird eine Bestimmung gewürckt §46. Folglich müßte die, durch diese Substanz, gewürckte Bestimmung ausser ihr hervorgebracht werden. Man kan diese Substanz demnach, in einem doppelten Zustande, betrachten, vor ihrer Handlung, und indem sie handelt. Wenn sie demnach durch ihre Handlung nicht selbst verändert würde, so bliebe sie, wenn sie die Handlung anfängt, noch völlig eben die Substanz, ohne die geringste Veränderung, die sie vorher, ehe sie handelt, gewesen. Da nun allezeit die Folgen einerley bleiben, wenn die Gründe einerley sind, (posita eadem ratione ponitur idem rationatum), so wird die angenommene Substanz, oder Kraft, in diesem ihrem doppeten Zustand einerley Würckungen verrichten. Vor der Handlung würckte sie nicht die Bestimmung, die durch diese Handlung soll hervorgebracht werden, sonst brauchte sie nicht zu handeln §46. Folglich wird sie auch in dem andern Zustand, wenn sie in der Handlung begriffen ist, keine Bestimmung hervorbringen, welches nicht nur dem Begriffe der Handlung widerspricht §46. sondern auch demjenigen, was angenommen werden müßte, wenn man meinen Lehrsatz leugnen wolte, zuwiderläuft.”

151. “Ich will zuerst die allerkeinste Substanz oder Kraft betrachten, und von derselben erweisen, daß sie unmöglich in eine andere physicalisch würcken könne. Es versteht sich von selbst, daß diese Substanz endlich ist, weil Gott die größte Kraft besitzt. Wolte man einwenden, daß keine Substanz würcklich vorhanden sey, die nur die allerkleinste wäre, so will ich das, um des allgemeinen Zusammenhanges in der Welt willen, zugestehen. Man nehme, an dessen statt, eine grössere Substanz, die aber ihre Kraft nur im niedrigsten Grade gebraucht. Man wird doch wohl diesen Fal zugestehen. Können denn nicht alle grössere Handlungen und Kräfte, mit Recht, als Inbegriffe der allerkleinsten Handlungen und Kräfte angesehen werden? Man setze also, die allerkleinste Kraft, oder eine grössere Substanz, die aber ihre Kraft nur im kleinsten Grade braucht. Diese Substanz kan nur die allerkleinste Handlung vornehmen §47. Kan aber diese Handlung ein reeller Einfluß seyn? Wir wollen es annehmen auf eine Zeitlang. Durch diese allerkleinste Handlung wird zuerst, eine Bestimmung in der kleinsten Substanz selbst, hervorgebracht §49, 50. Diese Bestimmung kan doch wohl nicht kleiner seyn, als die allerkleinste. Das kleinste ist ja eben dasjenige, welches, wenn es noch kleiner wäre, einen Wiederspruch enthielte. . . . Wenn also die allerkleinste Handlung einer endlichen Substanz ein reeller Einfluß seyn könnte, so müßten, durch die kleinste Handlung, wenigstens zwey allerkleinste Bestimmungen gewürckt werden, welches unmöglich ist §47.”

152. “So bleiben in jedem Fall viele Lücken in der Welt.”

153. “Dieser Einfluß wird nicht deswegen idealisch genennet, als wenn er kein würcklicher Einfluß wäre, und etwa nur eine blosse Vorstellung in der Seele, die außer der Seele keinen würcklichen Gegenstand habe, oder als wenn er wohl gar ein blosses Hirngespinste wäre. Sondern er wird deswegen so genennt, weil er erklärt werden kan aus Vorstellungen. Und zwar einmahl, aus den Begriffen, die Gott von Ewigkeit her, sich von diesen Substanzen, die in einander idealisch würcken, gemacht hat.”

154. See Stiebritz (1742–43) and Baumeister (1743).

156. There are, of course, other proponents of Physical Influx. While Crusius and Darjes might be classified broadly as rationalist, there were empiricist proponents of Physical Influx as well, such as Johann August Unzer. In his Gedancken vom Einfluß der Seele in ihren Körper (1746), Unzer gives an empiricist analysis of causation that allows for inter-substantial causation. In §24 (p. 60) Unzer states: “Wenn A ist, und B ist auch, wenn A nicht ist und B ist auch nicht; Wenn ferner dieses allemal geschieht; Wenn ich hernach auch as dem Wesen der Sachen begreiflich machen kan, daß entweder A eine Ursach von B sey: oder daß B, A würcke; Wenn endlich, wofern diese nicht seyn solte bey A und B die Regeln eintreffen, welche §12 gegeben worden sind; so ist es gewiß, daß zwischen diesen Dingen Ursach und Würckung statt habe. Nun kan man alles dieses von dem menschlichen Körper und seiner Sele behaupten; also würcken sie beyde in einander.” For an explanation of how others attempted to synthesize rationalist metaphysics with empirical observations during the latter half of the century in Germany, see Kuehn (1987).

157. Fabian (1925, p. 223) argues that Crusius makes no significant contribution on this issue: “Ebenso ungenügend und wenig überzeugend sind auch die Ausführungen des Philosophen Crusius.”

158. “eine jedwede Vereinigung zufälliger Dinge, welche außerhalb der Gedancke eine reale unio existentialis seyn soll, auf einer Causalverknüpfung der Dinge beruhen müsse, vermöge deren zum wenigsten eines gegen das andere thätig wircken muß, wiewohl auch beyde wechselweise gegen einander thätig seyn, und auch wechselweise voneinander leiden können. Denn es ist sonst nichts anders ausserhalb der Gedanke möglich, was einen Grund der Vereinigung zwischen vollständigen Dingen abgeben kan. Sobald man dahero dieses hinweg nimmt, so muß man sie nur durch einen Begriff im Verstande vereinigen, d.i. die Dinge haben alsdenn entweder gar keine oder doch nur eine bloß ideale Vereinigung. Daher kann ich z. E nicht einräumen, daß diejenigen, welche die prästabilirte Harmonie glauben, eine reale Vereinigung zwischen Leib und Seele übrig lassen. . . . Ihre Vereinigung ist bey Setzung dieser Meynung so far in Absicht auf GOtt selbst nur ideal. Man kan nicht einmal sagen, daß sie nur vermittelst der Darzwischentretung GOttes vereinigt werden. Denn alsdenn müßte doch GOtt zum wenigsten die Einrichtung des Wesens des Leibes und der Seele zugeschreiben werden können. Dieses cönnen aber die Vertheidiger der prästabilirten Harmony in dem rechten Leibnitzischen Verstande, nicht sagen, weil sie GOtt keine Ehre weiter übrig lassen, als daß er nur die Wesen der Substanzen zur Wirklichkeit gebracht, nicht aber eingerichtet habe, weil alle Wesen ewig sein sollen. Es bleibt dahero eine blosse Ubereinstimmung, nicht aber eine reale Vereinigung übrig.”

159. It may be that Crusius is insinuating other arguments here as well. For example, his allusion to the eternity of substances (and thus the world) is a consequence he clearly believes to contradict the Principle of Contingency (§33). He states the principle as follows: “that whose non-being can be thought really did not exist at one time, which one calls the Principle of Contingency” (dasjenige, dessen Nichtseyn sich denken läßt, wirklich einmal nicht gewesen sey, welches man den Satz von der Zufälligkeit nenn).

160. In his metaphysics lectures, Kant makes this kind of criticism as well.

161. At this point, it is appropriate to recall that Crusius advances a strongly voluntaristic position with respect to God. This position explains why Crusius is motivated to object to Leibniz in this manner.

162. This objection is similar to the Cartesian objection that the mind and the body are too distinct to act on each other.

163. In this context, Crusius adds that impenetrability is included in the general nature of the mind without noting that impenetrability and the capacity to move another body are not necessarily identical. However, in §402 of the Entwurf he does argue that impenetrability is the ground of moving another substance.

164. Crusius (1745, §419ff., p. 808ff.): “For if this were the case [this law of the conservation of motion were true], minds could cause no motion; and if said, that constantly a single sum of motion remains in the material world, then no part of the motion of matter could be used for the motion of the substance of minds. But then the material world would be of no use to minds, and they would have been created completely without a purpose”: “Denn wenn dieses wäre, so könnten die Geister keine Bewegung verursachen; und wenn sagt, daß in der materialen Welt beständig einerley Summe der Bewegung bleibe, so könnte auch kein Theil von der Bewegung der Materie auf die Bewegung der Substanz der Geister verwendet werden. Alsdenn aber wäre die materiale Welt den Geistern nichst nütze, und sie wäre völlig ohne Zweck erschaffen.” This reply is reminiscent of one of Reusch’s objections to Pre-established Harmony, though Crusius combines it with the objection to Physical Influx’s alleged violation of the law of the conservation of motion.

165. “§79.Dasjenige, was eine Ursache zu Hervorbringung eines Effectes beyträgt, verrichtet sie entweder 1) durch ihr blosses Daseyn, weil durch dasselbe die Existenz oder eine gewissen Art zu existiren eines andern Dinges möglich oder unmöglich, oder nothwendig gemach wird. . . . Wir haben solche Ursachen oben Existential-Gründe genennt. §36 Die Kraft derselben kan das unwircksame Vermögen eines Existential-Gründes heissen, (facultas existentialis). . . . Oder 2) die Ursache wircket vermittelst einer innerlichen Eigenschaft ihres Wesens, welche jetzo zu Hervorbringung dieses Effectes abgerichtet ist: So schreibet man ihr eine Activität oder Selbstthätigkeit zu. Sie heißt eine thätige Ursache und ihre Kraft eine thätige Kraft, (Facultas actiua) Es ist also eine thätige Kraft eine solche an eine Substanz verknüpfte Eigenschaft ihres innerlichen Wesens, vermögen deren durch sie etwas anderes wircklich ist, oder entstehet . . .

§ 80. Die in einem Object befindliche Schwierigkeit, die Action einer Ursache anzunehmen heißt die Reaction, oder der Wiederstand . . .

§ 81. In den thätigen Substanzen kan eine Thätigkeit wiederum von einer andern abhängen, von welcher sie eine Wirckung ist. Diese Reihe aber kan nicht unendlich fortgehen, sondern man muß zuletzt auf erste Actionen kommen, welche aus der Kraft der Subjecte nicht vermittelst einer andern Action, sondern unmittelbar entspringen, und nichts anders als die Anwendung der er-ersten Grundkräfte selbst sind. Ich will dieselben Grund-Thätigkeiten (actiones primas) nennen. Es lassen sich zweyerley Gattungen derselben dencken. Erstlich solche Grund-Thätigkeiten, welche vermöge des Wesens der Substanz beständig fortdauern, und welche eben das innerliche Wesen der thätigen Substanzen ausmachen. . . . Ferner läßt sich auch eine solche Art von Grund-Thätigkeiten dencken, welche nicht beständig geschehen.”

166. It is entirely possible that the distinctions that Crusius draws here are at least partially due to his acquaintance with late scholastics such as Suarez.

167. In §65 Darjes refers to Reusch’s Systema metaphysicum (1735) in order to suggest that the replies that defenders of Pre-established Harmony may make are inadequate.

168. Presumably due to problems of heterogeneity.

169. For an account of how Kant develops his own version of Physical Influx over time (in fact, throughout the Critical period), see Watkins (1995b).


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