Dal sistema al senso comune: Studi sul newtonismo e gli illuministi britannici (review)

360 HISTORY OF PHILOSOPHY extrinsic denominations. (2) Relations can be considered as extrinsic denominations only by abstracting from the interconnectionof all things. The way out of this apparent contradiction, Mugnai says, is to take Leibniz as regarding relations from two points of view. (a) From a purely logico-ontological point of view relations are extrinsic, in that they are determinations added to the thing by the intellect. (b) From a metaphysical aspect they are intrinsic, in that a change in a relation always implies a change in all the related terms. The view that relations can be regarded as intrinsic has profound consequences for the interpretation of Leibniz's philosophy, and it is worth asking if Mugnai has established it. What is crucial here is the proposition numbered above as (2). It is far from certain that this represents Leibniz's view; rather, he seems to mean that we can speak only of relations or of extrinsic denominations as long as we abstract from the interconnection of all things. That is, l_,eibniz is saying that relational terms are reducible to nonrelational terms. This view, which may be called the "reducibility thesis" about relations, has been ascribed to Leibniz by Bertrand Russell and (in a modified form) by others. Since Mugnai maintains that, in Leibniz's metaphysics, relations are intrinsic to a substance, he must take account of this interpretation, and he attempts this in chapter 8. He argues that Russell's interpretation confuses assertions that try to define the nature of relations with assertions that tend to reduce all propositions to the subject-predicate form (p. 163). Thus, when Leibniz says (to des Bosses, April 1714, Gerhardt, PS, 2:486) that the relation that is common to Solomon and his father David is "a purely mental thing" he is speaking of the ontological status of relations, not of the structure of relational propositions. Indeed (p. 169), Leibniz never tried to eliminate relational propositions, reducing them to propositions of subject-predicate form; relations (p. 177) form part of the complete concept of a substance, and have a basis in the eternal mind of God (pp. 163,179, 182). It may be doubted, however, whether this is sufficient to refute the view that Leibniz maintained a reducibility thesis. In particular, more attention might have been paid to those passages in which Leibniz states that when a substance changes its relations to others, there is some change in the substance itself--where "change" seems to mean a change in the substance 's predicates (Nouv. Ess. 2.25.5; Gerhardt, PS, 7:321-322; Couturat, Op., p. 520). This is a well-informed and thoughtful book, based on a careful study of the texts and displaying a wide knowledge of recent Leibnizianscholarship. In view of the fact that the author cites a number of Leibniz's works that are either wholly or partially unpublished (besides the works already cited, he refers on p. 167 n. to Bodemann, LH, VII B, III, 26, published only in part in Couturat, Op. pp. 286-287), it is somewhat regrettable that the original text of these works is not printed. However, this does little to detract from the merits of a scholarly piece of work. G. H. R. PARKINSON University of Reading Dal sistema al senso comune: Studi sul newtonismo e gli illuministi britannici. By Luigi Turco. (Bologna: 11Mulino, 1974. Pp. 354. Paper, L. 6,000) There is today a renewed interest in the work of Thomas Reid, the leader of the eighteenthcentury common-sense school. This is true particularly of Italy, where, in addition to Turco's book, various works on Reid have been pUblished in recent years: a volume edited and introduced by Antonio Santucci, Ricerca sulla monte umana e altri scritti di Thomas Reid (Torino, 1975), containing Italian translations of the Inquiry into the Human Mind, most of the Essays on the Intellectual Powers of Man and the first of the Essays on the Active Powers of Man; a BOOK REVIEWS 361 study by Franco Restaino, Scetticismo e senso comune: la filosofia scozzese da Hume a Reid (Bari, 1974); and a collection of essays by various authors, Scienza efilosofia scozzese hell'eta di Hume...