Routledge History of Philosophy Volume IV

DESCARTES: METHODOLOGY 181
9 There is one occasion on which Descartes does in fact make use of a form of argument
with a distinctively discursive structure: in his treatment of scepticism. Sceptical
arguments have a distinctive non-logical but nevertheless structural feature. They
rely upon the interlocutor of the sceptic to provide both the knowledge claims and
the definition of knowledge (i.e. the premises of the argument). The sceptic then
attempts to show a discrepancy between these two. Were the sceptic to provide the
definition of knowledge, or to provide knowledge claims or denials that certain
things are known, the ingenious dialectical structure of sceptical arguments would
be undermined. This is a very traditional feature of sceptical arguments, and it is a
sign of Descartes’s ability to handle it that he not only uses it to undermine
knowledge claims in the First Meditation, but he also uses it to destroy scepticism
in making the sceptic provide the premise of the cogito, by putting it in the form ‘I
doubt, therefore I exist’. In other words he is able to turn the tables on the sceptic
by using the same form of argument that makes scepticism so successful. But, of
course, once he has arrived at his foundation, he shuns this form of argument, for
now he has premises he can be certain of and so he no longer has any need to use
forms of argument which demand shared (but possibly false) premises.
10 It should be noted that ‘method’ was a central topic in the sixteenth century, but the
focus of the sixteenth-century discussion is different, and it derives from Aristotle’s
distinction between scientific and non-scientific demonstration. On the sixteenthcentury
disputes, see Neal W.Gilbert, Renaissance Concepts of Method (New
York, Columbia University Press, 1960).
11 For more detail on the problems of defining mechanism, see J.E.McGuire, ‘Boyle’s
Conception of Nature’, Journal of the History of Ideas 33 (1972) 523–42; and Alan
Gabbey, ‘The Mechanical Philosophy and its Problems: Mechanical Explanations,
Impenetrability, and Perpetual Motion’, in J.C.Pitt (ed.) Change and Progress in
Modern Science (Dordrecht, Reidel, 1985), pp. 9–84.
12 See K.Hutchison, ‘Supernaturalism and the Mechanical Philosophy’, History of
Science 21 (1983) 297–333.
13 See D.P.Walker, Spiritual and Demonic Magic from Ficino to Campanella
(London, the Warburg Institute, 1958).
14 Marin Mersenne (1588–1648) was one of the foremost advocates of mechanism,
and as well as writing extensively on a number of topics in natural philosophy and
theology he played a major role in co-ordinating and making known current work
in natural philosophy from the mid-1620s onwards. He attended the same school as
Descartes but their friendship, which was to be a lifelong one, began only in the
mid-1620s, during Descartes’s stay in Paris.
15 Averroes (c. 1126–c. 1198), the greatest of the medieval Islamic philosophers,
developed what was to become the principal form of naturalism in the later Middle
Ages and Renaissance. The naturalism of Alexander of Aphrodisias (fl. AD 200),
the greatest of the Greek commentators on Aristotle, does not seem to have been
taken seriously until the Paduan philosopher Pietro Pomponazzi (1462–1525) took
it up, and even then it was never explicitly advocated as a doctrine that presents the
whole truth. On the Paduan debates over the nature of the soul see Harold Skulsky,
‘Paduan Epistemology and the Doctrine of One Mind’, Journal of the History of
Philosophy 6 (1968) 341–61.
16 See Robert Lenoble, Mersenne on la naissance de mécanisme (Paris, Vrin, 2nd edn,
1971).