Princess Elisabeth and the Problem of Mind-Body Interaction*

Abstract

This paper focuses on Princess Elisabeth of Bohemia’s philosophical views as exhibited in her early correspondence with René Descartes. Elisabeth’s criticisms of Descartes’s interactionism as well as her solution to the problem of mind-body interaction are examined in detail. The aim here is to develop a richer picture of Elisabeth as a philosophical thinker and to dispel the myth that she is simply a Cartesian muse.

When philosophers recount the story of their past, they focus primarily on canonical figures. Historians of philosophy have initiated a movement, however, to uncover the work of minor figures in order to fill the gaps in this story and to provide a richer texture to our philosophical past. In the area of Descartes scholarship, for instance, a concerted effort has been made to find out who may have influenced René Descartes’s views and the figures that constituted the philosophical context in which he wrote. To this end, Princess Elisabeth of Bohemia has been the topic of discussion in many recent works on Descartes. The correspondence between Elisabeth and Descartes is thought to contain his mature views on the mind/body union, on ethics, and on politics. Stephen Gaukroger, for example, in Descartes: An Intellectual Biography (1995), devotes an entire chapter to this correspondence, and likewise in Vance Morgan’s Foundations of Cartesian Ethics (1994) the correspondence is a major focus.

Some feminist thinkers have also taken up the task of uncovering the work of minor figures in the history of philosophy—specifically women philosophers. Their aim is to uncover the ideas of women that have previously been overlooked. Princess Elisabeth is found in this literature as well. For instance, Andrea Nye in an article entitled “Polity and Prudence” (1996) argues that Elisabeth’s personal life led her to adopt views that diverge radically from Descartes’s. Nye writes, “Elisabeth’s initial and continuing objections to Descartes’s philosophy were not an adversarial finding of superficial inconsistencies but were generated out of immediate painful experiences as she dealt with constant conflicts between self-interest and duty to others, with the pain of inevitable regret and repentance and seemingly natural inclinations to certain kinds of behavior” (Nye 1996, 89).

Erica Harth in Cartesian Women (1992) suggests that Elisabeth offers Descartes an alternative epistemology, one more akin to contemporary feminist epistemologies that emphasize the subjectivity of the knower. Harth echoes the Bordoian ¹ interpretation of Descartes in the following passage: “As the relationship between the two correspondents deepened Elisabeth took charge of her own subjectivity and introduced it as a counterweight to what came to sound more and more like an axiomatic pronouncement on Descartes’s side. When, in the first several letters, the discussion centered on mathematics and natural philosophy, this subjectivity took the form of well-placed substantive doubts. . . . In May of 1645, Descartes and Elisabeth moved into the realm of moral philosophy with a proposed discussion of Seneca, [it was then that] she began to reflect on her own subjectivity and in effect proposed an alternative epistemology” (Harth 1992, 74).

These approaches to Elisabeth have led to a strange dichotomy of views about her. On the one hand, historians of philosophy, although they acknowledge Elisabeth as a formidable critic of Descartes, have remained, until recently, rather silent about Elisabeth’s philosophical views. She appears in this context as an inquisitive and critical student who entered philosophy through Descartes’s work. ² Feminist thinkers, on the other hand, have attempted to uncover Elisabeth’s philosophical views, but they have done so from a particular ideological perspective. In addition to seeing Elisabeth as a proto-feminist, their interpretations of her views seem to stem from assumptions about gender-based ethical and epistemological stances. Nye, for instance, juxtaposes what she calls Elisabeth’s “existential inquiry” (Nye 1996, 70) with Descartes’s rationalistic, objective, and defensive metaphysics. Such a reading, although interesting, imports the notion that there is a divide between the theoretical and the practical, the rational and the emotional, the objective and the subjective—a divide that feminist epistemologists and feminist philosophers of science have made much of in recent years. ³

Although both Descartes scholars and feminist thinkers have made valuable contributions to the history of philosophy and our understanding of Elisabeth, their approaches to her have been somewhat distorting. If we view Elisabeth’s philosophy as being motivated primarily by practical and existential concerns, her theoretical commitments may be overlooked and thus may lead to an incomplete understanding of her. Likewise, to view her simply as Descartes’s muse, as some historians have, is to trivialize her place in the history of philosophy. Her philosophical views can neither be dismissed nor serve ideological purposes until we have a richer picture of her as a thinker.

I develop such a picture by uncovering the philosophical assumptions and premises that she may have accepted rather than focusing on extra-philosophical considerations. ⁴ My focus is on the early correspondence between Descartes and Elisabeth and aspects of Elisabeth’s thought that arise there, in particular, her criticisms of Descartes’s interactionism and her solution to the problem of mind-body interaction. I hope to show that Elisabeth’s primary criticism of Descartes’s interactionism is a novel one and arose from careful consideration of Descartes’s physics. Her solution to the problem of mind-body interaction, although not a novel one, is worthy of consideration both because it reveals how Descartes’s contemporaries understood him and because several other thinkers of the time held the same view. Henry More, for instance, whose views I briefly discuss, suggested a solution to the problem of mind-body interaction that is similar in some respects to Elisabeth’s view. That Elisabeth’s view was part of the philosophical landscape of her time and that she was familiar with this landscape strongly suggest that Elisabeth neither entered philosophy exclusively through Descartes’s work nor were her views motivated simply by the practical concerns of life as a princess. In uncovering Elisabeth’s views on mind-body interaction and the way in which she understood Descartes’s work, I hope to reveal a depth to Elisabeth’s thought that some theorists have previously ignored.

I

In Elisabeth’s first letter to Descartes, dated May 16, 1643, she asks Descartes to clarify how the immaterial soul can cause the material body to act. Of course, her request is not an original one. Descartes’s view that the immaterial mind and the material body causally interacted troubled several other thinkers of the time. Pierre Gassendi, for instance, prompts Descartes to explain the way in which the mind and body are united and interact. Without an explanation of this unity, Gassendi assumes that the soul must be diffused throughout the body or located in the brain alone. If it is either in the body or a mere point in the brain, then it must take up some space, but this conclusion is impossible since Descartes argues that the soul is unextended. Gassendi writes, “If it is a physical point, the difficulty still stands, since such a point is extended and does not wholly lack parts. If it is a mathematical point, then such a point, as you are aware, is purely imaginary” (Gassendi 1985, 2:236). In the end, Gassendi rejects the view that the soul is unextended so as to make sense of the union of mind and body and their interaction.

Although Elisabeth’s request for Descartes to explain the interaction between mind and body falls in line with other Cartesian critics, the letter in which she raises the issue of interaction reveals a different emphasis. After requesting clarification of how the mind and body can influence one another, Elisabeth explains why she thinks that, given Descartes’s account of motion, interaction between soul and body is impossible. “For it seems every determination of movement happens from the impulsion of a thing moved, according to the manner in which it is pushed by that which moves it, or else, depends on the qualification and figures of the superficies of the latter. Contact is required for the first two conditions, extension is required for the third. You entirely exclude extension from your notion of the soul, and contact seems to me incompatible with an immaterial thing” (Blom 1978, 106; Descartes 1971, 3:661). ⁵ Elisabeth acknowledges, here, that Descartes’s theory of motion has different aspects; quantity of motion and determination. Since mind-body interaction is prima facie a form of motion, Descartes, according to Elisabeth, has to explain how both these aspects of motion are possible given that the soul is unextended and the body extended. In order to understand Elisabeth’s objection a short digression into Descartes’s physics is required.

In the Optics (Descartes 1985, vol. 1) the distinction between motion and determination arises in Descartes’s discussion of the laws of reflection and refraction in which he uses four analogies to reveal how the behavior of light is determined. In his discussion of reflection, he considers the motion of a tennis ball when it hits the surface of the ground. In his discussion of refraction, he considers the motion of the ball when it hits the surface of a cloth and the surface of a body of water, and when a racket adds motion or speed to the ball. For our purposes we can focus on Descartes’s discussion of reflection.

In the figure, CBE is the surface of the ground and the ball is impelled from A to B. Descartes’s task is to explain how the ball will behave and to infer from this behavior how light will behave when it hits a mirror. For the purposes of avoiding difficulties, he assumes that the ground is perfectly flat and hard and that the ball travels at a constant speed. He also leaves “aside entirely the question of the power which continues to move it (the ball) when it is no longer in contact with the racquet, and without considering any effect of its weight, size and shape” (1985, 1:157). To figure out which way the ball will go Descartes appeals to the distinction between determination and motion. He writes, “It is only necessary to note that the power of whatever it may be which causes the ball to continue moving is different from that which determines it to move in one direction rather than another” (1985, 1:157). The following passage supports this view: “It is very easy to recognize this from the fact that the movement of the ball depends upon the force with which it had been impelled by the racquet, and this same force could have made it move in any other direction as easily as towards B; whereas the ball’s tending towards B is determined by the position of the racquet, which could have determined the ball in the same way even if a different force had moved it” (Descartes 1985, 1:157).

Descartes claims that the speed or motion of the ball depends on how forcefully it is hit, but its subsequent determination is a function of the racquet or its surface when the ball is hit. The racquet, for instance, if slightly tilted, will change the determination of the ball. Further, the determination can change without there being a change in the quantity of motion. “This in itself shows that it is not impossible for the ball to be deflected on colliding with the ground, and therefore for the determination to tend towards B to be changed, without there being thereby any change in the force of its motion, since these are two different things . . .” (Descartes 1985, 1:157).

After making the distinction between determination and motion, Descartes argues that the ball must rebound towards F. I will not consider this argument here for it is beyond the scope of this paper. I would like to point out, however, a similarity between Descartes’s discussion of the movement of the ball and Elisabeth’s account of the determination of motion in her first letter. Consider again the passage from Elisabeth’s letter of May 1643:

For it seems every determination of movement happens from the impulsion of a thing moved, according to the manner in which it is pushed by that which moves it, or else, depends on the qualification and figures of the superficies of the latter. Contact is required for the first two conditions, extension is required for the third. You entirely exclude extension from your notion of the soul, and contact seems to me incompatible with an immaterial thing.

(Blom 1978, 106; Descartes 1971, 3:661; italics added)

Elisabeth notes here that there is an aspect of motion that is dependent on the qualities and figure of the object with which the moving body comes in contact. This aspect is clearly Descartes’s notion of determination. As Descartes tells us, the determination of an object depends on the qualities (position, superficies, etc.) of the object it meets in collision. He writes: “. . . consider that a ball passing through the air may encounter bodies that are soft or hard or fluid. If these bodies are soft, they completely stop the ball and check its movement, as when it strikes linen sheets or sand or mud. But if they are hard, they send the ball in another direction without stopping it, and they do so in many different ways. For their surface may be quite even and smooth, or rough and uneven; if even, either flat or curved; if uneven, its un-evenness may consist merely in its being composed of many variously curved parts, each quite smooth in itself . . .” (Descartes 1985, 1:155).

In Descartes’s discussion of the tennis ball, the position of the racket and the qualities of the ground alter the ball’s determination. Elisabeth’s claim that “every determination of movement happens from the impulsion of a thing moved, according to the manner in which it is pushed by that which moves it, or else, depends on the qualification and figures of the superficies of the latter” (Blom 1978, 106; Descartes 1971, 3:661; italics added) is strikingly similar to Descartes’s own account of the determination and movement of the tennis ball. This is not surprising given that Elisabeth’s only access to Descartes’s theory of motion would have been through reading the Optics. Descartes gives the most complete account of his theory of motion in the Principles (Descartes 1985, vol. 1), but this work was not written at the time she wrote her first letter to Descartes in 1643. The only published work available at that time that contained Descartes’s views on motion was the Discourse on Method to which the Optics was attached. That Elisabeth read the Optics and was aware of the distinction between motion and determination is evidenced by her mention of the distinction in a later letter dated May 24, 1645. She writes of Sir Kenelm Digby’s treatise: “I hoped to take from it arguments to refute yours, since the summary of the chapters showed me there were two places where he pretended to have done it; but I was completely astonished when I reached those points to see he had understood nothing less than what he approved of in your view concerning reflection, and that, because of his misunderstanding, he denies what you say of refraction, as he fails to make any distinction between the movement of a ball and its determination, and does not give consideration to why a soft body that gives way retards the one, and why a hard body only resists the other” (Blom 1978, 122; Descartes 1972, 4:209–10).

This passage reveals clearly that Elisabeth recognized the distinction between determination and motion and understood Descartes’s view that determination may change while motion remains the same. I see no reason to think that she did not understand this when she wrote her first letter in 1643 especially since, as we have seen, the first letter contains elements similar to Descartes’s discussion of determination and motion in the Optics. For these reasons I think it is unlikely that Elisabeth used the phrase determination of movement unwittingly. ⁶

What Descartes meant by determination has been, and continues to be, the subject of much dispute. Early commentators on Descartes’s Optics interpreted determination as direction. Pierre Fermat, for instance, understood Descartes to have associated determination solely with direction; he seems to have interpreted Descartes as saying determination may exist without speed or speed may exist without determination. Descartes, however, insisted that determination was not merely direction.

If determination is not to be equated with direction, how is it to be defined? Several commentators have offered clarifications of Descartes’s notion of determination. A. I. Sabra, for instance, suggests that Descartes’s distinction between motion and determination corresponds to the distinction between vector and scalar quantities ⁷ and in “Force and Inertia in The Seventeenth Century: Descartes and Newton,” Alan Gabbey suggests that Descartes’s determination should be defined as “a directional mode of motive force” (Gabbey 1980, 260). Assessment of these suggestions is beyond the scope of this paper. It is enough to note that Descartes’s contemporaries understood determination to be an aspect of motion involving direction. It is likely that Elisabeth shared this understanding of the term.

If we accept, then, that Elisabeth’s initial criticism of Descartes’s interactionism reveals an emphasis on (or at the very least an acknowledgement of) the notion of determination, the following questions arise: How is the determination of motion related to the problem of mind-body interaction? And why might Elisabeth have been concerned to point out this aspect of motion?

Gabbey provides us with the beginnings of an answer to these questions. In addition to offering a clarification of the term, Gabbey points out that the use of determination in Descartes parallels the Thomistic distinction between an indeterminate cause and its determinate effects. He writes, “The Thomistic-Cartesian doctrine of the divine creation and conservation of the world, according to which God maintains his creation in existence by lending it so to speak its esse, carries with it the need to link in some way the universal divine conserving power to its multiple and diverse appearances in the world. If there is to be diversity in the divinely-maintained corporeal world, there must be principles of diversification. For Descartes these principles are speed and determination, just as for Aquinas determination is the first principle of plurality” (Gabbey 1980, 261). If Gabbey is correct, then Descartes’s use of the term determination reveals an awareness that simply one body’s adding of motion to another body (or God’s adding of motion to the world) is not enough to explain the diversity of effects one body can have on another. Elisabeth’s interest in the notion of determination can be viewed as exhibiting a similar awareness.

Throughout the correspondence Elisabeth reveals a deep concern with the relationship between metaphysics and moral philosophy. This is evident in her original request to Descartes to clarify how the mind and body interact. Elisabeth writes, “. . . I beseech you to tell me how the soul of man (since it is but a thinking substance) can determine the spirits of the body to produce voluntary actions” (Blom 1985, 106; Descartes 1971, 3:661; italics added). Based on the idea that we are held responsible for voluntary actions, Elisabeth’s letter reveals that she sees the interaction between mind and body to be the source of such actions. Voluntary actions result from the mind freely causing the body to act in a particular way—in a determinate manner. Hence, a foundation for morality must include an understanding of how mind and body interact and how each produces a diversity of effects in the other. Elisabeth recognized that for the soul to be responsible for voluntary actions it must be in control. Simply adding motion to the body is not enough. The soul must be able to determine the direction that motion takes.

The issue of how the soul is to control the body is a subject to which the correspondence between Elisabeth and Descartes continually returns. In an effort to provide Elisabeth with a cure for her own physical and emotional ailments, Descartes suggests a psychosomatic solution in which the mind can cure the body by thinking positive thoughts. In a letter dated May or June 1645 he writes: “. . . one must deliver one’s mind entirely from all sorts of sad thoughts, and also even from all serious meditations regarding the sciences, and occupy oneself only at imitating those who, in looking at the verdure of a wood, the colors of a flower, the flight of a bird, and such things as require no attention, convince themselves that they are not thinking of anything” (Blom 1978, 125; Descartes 1972, 4:220). Although grateful for Descartes’s advice, Elisabeth points out that one’s physical constitution can often impede one in overcoming melancholy. She reaffirms this view in their discussion of how one is to attain the sovereign good. Elisabeth reminds Descartes that the will is sometimes not able to control a body that is physically impaired. She writes, “And thus, as yet, I am unable to extricate myself from doubting that one can arrive at the beatitude of which you speak without assistance of what does not depend absolutely upon the will; for there are maladies that completely deprive one of the power of reasoning, and consequently of enjoying a reasonable satisfaction; others diminish the force of reasoning and prevent one from following the maxims that good sense would institute . . .” (Blom 1978, 135; Descartes 1972, 4:269).

Elisabeth’s interest in the notion of determination, then, can be seen as a natural outcome of her concern over how the mind is to control the body, especially one that is physically impaired. The physically impaired body often overwhelms reason, and Elisabeth wants to know what can be done to curb its influence. She also wants an explanation of how it is that the body can have the power to produce various effects, such as pain and pleasure, in the soul. Again, the ability to add motion to the soul does not seem to provide an explanation of how it can produce such radically different effects as pain and pleasure. Indeed, one might view Elisabeth’s request (in her letter of September 13, 1645) for Descartes to define the passions as a request for an explanation of how the body and soul interact to produce a variety of different effects in one another. “I would also wish you to define the passions, so that they be well known; for those who name them perturbations of the soul would persuade me that the force of the passions consists only in overwhelming and subjecting reason, had not experience shown me there are passions that carry us to reasonable actions” (Blom 1978, 149; Descartes 1974, 4:289–90). The passions do not “overwhelm” reason in an indeterminate manner. As Elisabeth points out, the passions seem to be able to direct reason (in the sense of determining its movement) in ways that can produce either reasonable or unreasonable action.

After attempting to show that Descartes’s theory of motion is incompatible with mind-body interaction, Elisabeth raises the following request: “. . . I ask of you a definition of the soul more particular than in your metaphysics—that is, a definition of the substance separate from its action, thought” (Blom 1978, 106; Descartes 1971, 3:661). Her request here suggests that she may have been working within a scholastic framework.

Descartes adopted from the scholastics the notions of substance, attribute, and mode. In the Principles Descartes defines substance as “an existent thing which requires nothing but itself in order to exist” (Descartes 1985, 1:210). According to Descartes, we do not perceive substances as such but only the attributes of substances. “We cannot initially become aware of a substance merely through its being an existent thing, since this alone does not itself have any effect on us. We can, however, easily come to know a substance by one of its attributes . . .” (1985, 1:210). We do not, however, have equal access to all of the attributes of a substance. We have access to one attribute that determines the nature of the substance. Descartes claims, “there is always one principal property of substance which constitutes its nature and essence and on which all others depend” (1985, 1:210).

Daniel Garber points out in Descartes’s Metaphysical Physics that Descartes diverged from the scholastics in that he thought all of the properties of a body or soul are intimately linked to the essence of a substance (Garber 1992, 68). The scholastics acknowledged that certain accidents were nonessential but connected to the essence of substance in important ways—they called these accidents properties (propria) and proper accidents (accidentia propria). These properties and proper accidents could be understood only through the essence of the substance. For instance, risibility, a property found in humans, though not essential to humans, cannot be understood apart from an understanding of what it is to be human. The Scholastics also acknowledged that certain accidents are not connected to the essence of the substance but are simply “tacked” onto the substratum. These accidents are not necessarily conceived through the essence of the substance. Descartes rejected these latter accidents. For Descartes, all accidents are to be intimately linked to the substance. This can be seen, according to Garber, in Descartes’s choice of the term mode to characterize the accidents of body and soul. The accidents of material substance are literally ways of being extended, and the accidents of immaterial substance are literally ways of being a thinking thing.

Given that for Descartes thinking is a mode of immaterial substance and that all other properties of the soul must be considered through this essential mode, what can be made of Elisabeth’s request that he say more about the substance apart from its action? Descartes’s use of the term mode appears in his replies to Thomas Hobbes’s objections. ⁸ Elisabeth had access to the Meditations (in Descartes 1985, vol. 2) and to the objections and replies; her letters provide evidence of her familiarity with them. For instance, Elisabeth uses Antoine Arnauld’s objection that if the soul is viewed as essentially a thinking thing, then even infants and those who are unconscious must be thinking. One might think, then, that Elisabeth’s request for Descartes to say more about the substance apart from its activity betrays a misunderstanding. That is, one might claim that she had failed to see the importance of Descartes’s use of mode and how closely he linked a substance with its attributes.

In a more charitable vein, however, Elisabeth’s request might be viewed as a challenge to Descartes’s idiosyncratic use of traditional scholastic notions. ⁹ Elisabeth accepts that the soul and its activity are somehow inseparable, but she suggests that there is still a way in which the soul might be looked at apart from its principal attribute; in addition, she thinks there might be a way to consider the other attributes of the soul apart from its essential attribute. She writes, “For although we suppose them (the soul and its attributes) inseparable (which nonetheless is difficult to prove regarding infants in their mother’s womb and deep faints) still like the attributes of God, we can, by considering them separately, acquire a more perfect idea of him” (Blom 1978, 106; Descartes 1971, 3:661). This suggests that Elisabeth is working within a more Scholastic framework. The soul’s attributes are not distinct from the soul but perhaps, as Francisco Suarez suggests, a distinction in reason (distinction of the reasoning reason, distinctio rationis ratiocinantis) is to be made, one that would allow the soul to be considered apart from its essential mode and its other attributes to be considered apart from its essential mode. Elisabeth’s request for Descartes to say more about the attributes of the soul, then, need not be seen as a misunderstanding of his view but as evidence of her scholastic understanding and her dissatisfaction with Descartes’s nonstandard use of the traditional scholastic notions.

Elisabeth’s focus on what the substance is apart from its activity as well as her focus on the soul’s other attributes foreshadows the introduction of her solution to the problem of interaction. Recall what Descartes claims: all other attributes of a substance depend on one principal attribute. Elisabeth wants Descartes to consider what those other attributes might be. She is convinced that a closer look will reveal an attribute of the soul, previously overlooked by Descartes, that will explain how the mind and body can interact.

Descartes’s reply dated May 21, 1643 attempts to comply with Elisabeth’s request that he define the substance (soul) apart from its action (thinking). He acknowledges that he has not considered every aspect of the soul and he writes, “there being two things in the human soul on which depend all the knowledge we can have of its nature—the first that it thinks, and the second that it being united to the body it can suffer and act with it—I have said nearly nothing of this latter . . .” (Blom 1978, 107–8; Descartes 1971, 3: 664–65). Descartes goes on to write that although his metaphysics focuses on the first way of knowing the soul, because he was interested in establishing the distinction between the soul and the body, he will try to say “how he conceives of this unity and how it has the force to move the body” (Blom 1978, 108; Descartes 1971, 3:665).

He continues by laying out the now familiar doctrine of the three primitive notions. ¹⁰ All our knowledge is built upon three primitive notions within us. The notion of extension is used to build knowledge of the body. The notion of thought is used to build knowledge regarding the soul alone. For the unity of the soul and body there is the primitive notion of their union. Knowledge is gained by a clear distinction of these notions and care must be taken not to apply them to things to which they do not apply. For instance, because extension is the most familiar of these notions it is often applied to the nature of the soul in order to explain how the soul can move the body. According to Descartes, this application is a mistake. Although all these notions are in the soul, they are not always distinguished or applied correctly. “Thus I believe that we have hitherto confused the notion of the force by which the soul acts on the body with that by which one body acts upon another” (Blom 1978, 109; Descartes 1971, 3:666–67). Descartes provides Elisabeth with a somewhat obscure analogy to explain how notions are sometimes misapplied, and in the process seems to provide a way to explain interaction between mind and body. “For example, in supposing weight (to be) a real quality, of which we possess no other knowledge save that it has the force of moving the body in which it exists toward the center of the earth, we have no difficulty conceiving how it moves this body, nor how it is joined to it; and we do not think that happens by means of an actual touching of one surface against the other, for we experience in our own selves that we have a particular notion for conceiving it; yet I believe that in applying this notion to weight—which, as I hope to show in my physics, is nothing really distinct from the body—we are abusing what has been given us for conceiving the manner in which the soul moves the body” (Blom 1978, 109; Descartes 1971, 3:667).

In the final sentence of the last passage, Descartes tells Elisabeth that a notion for understanding the interaction between mind and body has been previously misapplied to the case of weight. Yet it is not at all clear how this notion should be abstracted from the case of weight. However Descartes’s analogy is understood here, it seemed to be unhelpful to Elisabeth. She is clear that she does not find in it an answer to how mind-body interaction occurs. In a letter of June 20, 1643 she writes: “. . . excuse my stupidity in being unable to comprehend, from what you had previously said concerning weight, the idea by which we should judge how the soul (nonextended and immaterial) can move the body; nor why this power, that you have then under the name of quality falsely attributed to it as carrying the body toward the center of the earth, ought to persuade us that body can be pushed by something immaterial any more than the demonstration of a contrary truth (as you promise in your physics) confirms us in the opinion of its impossibility” (Blom 1978, 111; Descartes 1971, 3:684).

She goes on to say that it is easier for her to conceive of the soul as extended than to conceive of the immaterial soul as having the capacity to move and be moved. At this juncture Elisabeth points out another conflict between Descartes’s views and mind-body interaction. She does not focus on the determination of motion, but rather she raises a difficulty concerning the medium responsible for conveying messages from the mind to the body and from the body to the mind. She writes, “For, if the first (moving of the body by the soul) occurred through ‘information,’ the spirits that perform the movement would have to be intelligent, which you accord to nothing corporeal” (Blom 1978, 112; Descartes 1971, 3:685). That is, the spirits, after the soul moves them, would have to carry these messages in an intelligible form to the body parts. In Descartes’s system, because the spirits are corporeal and not “intelligent,” this would be impossible. Likewise, according to Elisabeth, Descartes has excluded the possibility of the material body moving the soul. She writes: “Although in your metaphysical meditations you show the possibility of the second (the soul being influenced by the body), it is, however, very difficult to comprehend that a soul, as you have described it, after having had the faculty and habit of reasoning well, can lose all of it on account of some vapors, and that, although it can subsist without the body and has nothing in common with it, yet is so ruled by it” (Blom 1978, 112; Descartes 1971, 3:685). Elisabeth claims that the possibility of matter influencing an immaterial soul is even more incomprehensible given that the two are distinct and that reason is granted to the latter. How is it possible for the soul to lose its reason by simply being affected by some unintelligent vapors?

Although Elisabeth’s concerns here about the “intelligence” of the spirits are different from those that focus on the notion of the determination of motion, both concerns stem from her interest in how the soul can cause voluntary actions (in the body) and how the body can produce diverse effects in the soul. Just as it is not enough for the soul to simply add motion to the body in order to account for voluntary action, it is not enough that the spirits be able to move the muscles to account for the determinate ways in which they do move. The spirits must be able to give educated commands to the body. Likewise, to explain the diverse ways in which the body affects the soul one must appeal to more than the body’s ability to add motion to the animal spirits. One must, according to Elisabeth, appeal to the intelligence of those animal spirits—an intelligence that Descartes’s system denies them.

In a letter dated June 28, 1643, Descartes attempts again to answer Elisabeth’s questions. He returns to his three notions and suggests that what he should have done previously was reveal the distinction between these notions. The notions can be distinguished by considering how the soul conceives of itself, extension, and the union of body and soul. It is through the pure understanding that the soul conceives of itself, and through the understanding aided by the imagination that one conceives of extension. The senses alone know the unity of body and soul most clearly. Metaphysics can help us to know the soul more clearly, whereas mathematics can aid us in gaining a better understanding of extension. Only everyday life and conversation, however, allow us to conceive of the unity of mind and body. Descartes suggests that it is Elisabeth’s metaphysical speculations that are preventing her from comprehending the unity of mind and body. “But I have judged that it was those meditations rather than thoughts that require less attention, that have made her find obscurity in the notion we have of their union; for it does not seem to me that the human mind is capable of conceiving very distinctly, and at the same time, both the distinction between the soul and the body, and their union; because to do so it is necessary to conceive of them as one thing alone, and at the same time to conceive them as two, which is contrary” (Blom 1978, 114; Descartes 1971, 3:693).

Descartes seems to have mistaken Elisabeth’s concerns over how the mind and body interact for a lack of ability to conceive of the union. But Elisabeth is quick to point out in her reply dated July 1, 1643 that she does not lack the ability to conceive of their union but lacks the knowledge of how their interaction is possible given Descartes’s physics. Elisabeth at this point presents her own solution to the problem:

I too find that the senses show me that the soul moves the body; but they fail to teach me (any more than the understanding and the imagination) the manner in which she does it. And, in regard to that, I think there are unknown properties in the soul that might suffice to reverse what your metaphysical meditations, with such good reasons, persuaded me concerning her inextension. And this doubt seems founded upon the rule you lay down there in speaking of the true and the false—namely, that all our errors occur from forming judgements about what we do not sufficiently perceive. Although extension is not necessary to thought, yet not being contradictory to it, it will be able to belong to some other function of the soul (no) less essential to her.

(Blom 1978, 117; Descartes 1972, 4:2) ¹¹

Recall that in Elisabeth’s first letter to Descartes she asks him to consider the other attributes of the soul. Here she has returned to this idea. There may be an attribute of the soul, no less essential, which is extended and this extension explains how the soul can move the body and how the body can move the soul. Descartes does not respond to this suggestion. Given his view that the soul has only one essential attribute, he probably found Elisabeth’s suggestion unacceptable. The correspondence shifts at this point from the topic of mind-body interaction to Elisabeth’s health and from there to discussions of moral goodness, the passions, and free will. No mention of Elisabeth’s suggestion occurs in the rest of the correspondence. Although the suggestion that the soul is extended is not one which Descartes’s metaphysics could embrace, it should be noted that this was a common view at the time. In order to provide some historical and philosophical context for Elisabeth’s suggestion that the soul is somehow extended I will briefly turn to the views of Henry More.

II

Henry More also considered Descartes’s theory of motion to be inconsistent with the interaction of mind and body. But his reasons for thinking so are different from Elisabeth’s. Rather than focusing on the notion of determination or on the intelligence of the medium responsible for motion, More’s criticism focuses on Descartes’s view that the total quantity of motion is conserved. The principle cause of motion on Descartes’s account is God, and from this Descartes derives his conservation principle: God preserves the same amount of motion and rest in the universe that he originally put there. To More this principle rules out the possibility that the soul could initiate a new motion and move the body. In a letter dated July 23, 1649 he raises this problem to Descartes: “I ask: when the mind stirs the animal spirits by thinking more attentively and for a longer time and, moreover, rouses the body itself, doesn’t it surely then increase the motion in the universe?” (Descartes 1974, 5:385).

In addition to being concerned with the law of conservation of motion, More is also concerned with Descartes’s identification of matter and extension. More’s basic criticism of Cartesian dualism is that he cannot see how something that does not have extension, namely the soul, can be joined to something purely material—the body. “Is it not better to assume that the soul, though immaterial, is also extended; indeed that everything, even God, is extended?” (Descartes 1974, 5:183). More argues that the concept of extension should not be applied simply to matter but to everything that exists. This application explains how God can be “in” the world. Instead of defining matter in terms of extension, it should be defined in terms of its relation to the senses. Through the senses we experience the tangibility of matter, and so matter should be defined, according to More, in sensory terms. “I will define therefore a Spirit in general thus, a substance penetrable and indiscernible. The fitness of which definition will be better understood, if we divide substance in general into these first kinds, viz. Body and Spirit, and then define Body to be a substance impenetrable and indiscernible” (More 1969, 67). More acknowledges that Descartes’s theory is not one of sense perception; so he suggests that if matter is not defined by its tangibility then it should be defined in terms of its impenetrability. It is this attribute that separates matter from soul.

There are some interesting similarities and points of divergence in the criticisms of More and Elisabeth. More is unhappy with Descartes’s definition of matter because he is convinced that extension applies to the soul and God. Elisabeth is unhappy with Descartes’s definition of the soul; she pushes him to consider its other attributes because she is convinced that to explain the interaction between mind and body the soul must have an extended element. Further, both More and Elisabeth attempt at some point to show that Descartes’s theory of motion excludes the possibility of a purely immaterial soul interacting with a material body.

Although More’s view is similar to Elisabeth’s in some respects, he is not the source of Elisabeth’s thinking on this matter. More’s correspondence with Descartes occurred in 1649, and his treatise on the immortality of the soul was published in 1659. Elisabeth’s suggestion that the soul is extended and her criticisms of Descartes’s interactionism occurred in the early letters of 1643. ¹² What, then, is the source of Elisabeth’s views? Perhaps Elisabeth’s views on the extension of the soul were a result of Descartes’s own suggestion in Meditation II (Descartes 1985, vol. 2) that some features of the soul were unknown to him. Descartes writes, “I am not the concatenation of members we call the human body. Neither am I even some subtle air infused into these members, nor a wind, nor a fire, nor a vapor, nor a breath, nor anything else I devise for myself. For I have supposed these to be nothing. But perhaps it is the case that these very things which I take to be nothing, because they are unknown to me, nevertheless are in fact no different from the ‘me’ that I know? This I do not know, and I will not quarrel about it now. I can make a judgment about things that are known to me” (Descartes 1985, 2:18). Elisabeth was also familiar with Hobbes’s and Gassendi’s objections to Descartes’s Meditations, and both critics held the view that the soul was extended. Perhaps Elisabeth found their views appealing and adopted the view of an extended soul for herself, or perhaps she arrived at this view after considering the inadequacies of Descartes’s theory. That Elisabeth’s solution to the mind/body problem was not hers originally does not, however, take away from the fact that Elisabeth was engaged in philosophical thought and had her own philosophical views.

I have attempted to make sense of Elisabeth’s criticisms of Descartes and her solution to the problem of mind-body interaction by considering her philosophical motivations and the assumptions that she may have accepted. My account of what motivated Elisabeth to focus on the determination of motion and her interest in the “intelligence” of the spirits remains, of course, speculative, but my reading of her may provide a way of understanding how Elisabeth’s letters on mind-body interaction are linked to her later correspondence, wherein she focuses on moral philosophy, the passions, and free will.

Writers such as Nye and Harth have pointed out that in her later correspondence Elisabeth exhibits a practical rather than theoretical approach to questions of morality. Although beyond the scope of this paper, I think it would be profitable to reconsider her ethical views in light of the metaphysical views she expresses in her early correspondence. It might be found that her ethical views are motivated, at least initially, by theoretical commitments rather than, as Nye suggests, “immediate painful experiences” (Nye 1996, 89).

I hope to have shown in this cursory look that Elisabeth’s motivation for criticizing Descartes arose from a careful consideration of his science and not, as some feminist philosophers have suggested, from her experience as an embodied subject. Likewise, I think this closer look at Elisabeth’s criticisms of Descartes and her view of the soul as extended dispels the myth that she was simply a Cartesian muse.