Cartesian Method and the Problem of Reduction (review)

612 JOURNAL OF THE HISTORY OF PHILOSOPHY 30:4 OCTOBER 199 2 October 1629; Castelli to Galileo, 6 April 163o.... But this is a small fault, an omission that (one hopes) will be remedied in a later edition. ERNAN McMuLLXN Universityof Notre Dame Emily R. Grosholz. Cartesian Method and the Problem of Reduction. New York: Oxford University Press, 1991. Pp. viii + 161. Cloth, $4e.5 o. Philosophers write about other philosophers for a wide variety of reasons. One of them is the feeling that they have gone wrong and have caused philosophy to veer in the wrong direction. It is one of the virtues of Emily Grosholz's book that she does not disguise her "negative animus" towards Descartes and his baneful influence on twentieth-century philosophers. She sees the rot at work in the "eliminative reduction" prevalent among those who would replace philosophical discourse with the description of neural states. I say this is a virtue because we can learn much from Emily Grosholz if we realize that her target is not so much Descartes, the seventeenth-century recluse and sage, but the Churchlands and contemporaries of the same ilk. As far as the historical Descartes is concerned, I cannot help wondering whether he would not find that he has been greatly reduced, not only in stature and reputation, but in what he would take, if not for his philosophy, at least for his philosophical intent. Emily Grosholz writes her book as a critique of Descartes. Without taking up the cudgels for her opponent, I have the easier task of introducing her work to an audience that can make up its own mind about the merits of her indictment of Cartesian philosophy. The book opens with two interesting chapters on Descartes's Geometrywhere the relation of Descartes's mathematics to his method is scrutinized and shown to be at variance with the common belief that it is simple and straightforward. The limitations of Descartes's approach are stressed and the reader is reminded that the French philosopher was no Leibniz. Chapter 3 expounds some of Descartes's difficulties in formulating the basic notions of his cosmology as it appeared in the Principles ofPhilosophy of 1644. Chapter 4 discusses the infamous Cartesian laws of motion. Chapter 5 purports to provide the context of Cartesian physics but can more properly be said to address his treatment of freely falling bodies and projectile motion. Chapter 6 offers an analysis of Descartes's physiology where the scientific advantages are seen to have been purchased at an exorbitant epistemological price. The concluding chapter, which is in many ways the most interesting, is a re-examination of Descartes's Meditations in the light of Grosholz's interpretation of his method as intuitionist and reductionist. She initially follows Martial Gueroult's persuasive reconstruction of Descartes's "ordre des raisons," but she soon turns him into a sparring partner. He is obviously in her league, hut unable to fend off her trenchant arguments against the way Descartes reduces the idea of material extension to a property of the unextended mind. Faced with these difficulties, Gueroult changes tack and circumvents them like shoals in an otherwise placid sea. Emily Grosholz has produced a lively and persuasive account of the dangers that BOOK REVIEWS 613 beset reductionism. I am sorry, however, that she did not choose to quote one of the rare texts that I have come across where Descartes explicitly mentions reduction. The passage occurs in his notebook for the years i619-169I, and is a reference to the celebrated mnemonist Lambert Schenkel to whom Descartes paid the unusual compliment of reading his book on the art of memory. "I thought," writes Descartes, "of an easy way of making myself master of all I discovered through the imagination. This would be done through the reduction of things to their causes. Since all can be reducedto one it is obviously not necessary to remember all the sciences." Descartes then offers an interesting improvement of the way that images can be constructed to assist in the recollection of the causal chain. There are many kinds of reductions in Descartes, some are successful, like the one he performs with his compass...