Routledge History of Philosophy Volume IV

deduction from truths of reason is, almost by definition, constitutive of
epistemology, and a reading of a number of passages in Descartes in which he
discusses his project in highly schematic terms as accounts of his method of
discovery. The reading of Descartes as founder of a school is largely a
nineteenth-century doctrine first set out in detail in Kuno Fischer’s Geschichte
der neueren Philosophie in the 1870s. There is a hidden agenda in Fischer which
underlies this: he is a Kantian and is keen to show Kant’s philosophy as solving
the major problems of modern thought. He sets the background for this by
resolving modern preKantian philosophy into two schools, rationalism and
empiricism, the first basing everything on truths of reason, the second basing
everything on experiential truths. This demarcation displaces the older Platonist/
Aristotelian dichotomy (which Kant himself effectively worked with), marking
out the seventeenth century as the beginning of a new era in philosophy, one
dominated by epistemological (as opposed to moral or theological) concerns. 3
This reading of Descartes is not wholly fanciful, and it has been widely
accepted in the twentieth century by philosophers who do not share Fischer’s
Kantianism. On the face of it, it has considerable textual support. Article 64 of
Part II of Descartes’s Principles of Philosophy is entitled:
That I do not accept or desire in physics any principles other than those
accepted in geometry or abstract mathematics; because all the phenomena
of nature are explained thereby, and demonstrations concerning them
which are certain can be given.
In elucidation, he writes:
DESCARTES: METHODOLOGY 157
For I frankly admit that I know of no material substance other than that
which is divisible, has shape, and can move in every possible way, and this
the geometers call quantity and take as the object of their demonstrations.
Moreover, our concern is exclusively with the division, shape and motions
of this substance, and nothing concerning these can be accepted as true
unless it be deduced from indubitably true common notions with such
certainty that it can be regarded as a mathematical demonstration. And
because all natural phenomena can be explained in this way, as one can
judge from what follows, I believe that no other physical principles should
be accepted or even desired. 4
This seems to be as clear a statement as one could wish for of a method which
starts from first principles and builds up knowledge deductively. Observation,
experiment, hypotheses, induction, the development and use of scientific
instruments, all seem to be irrelevant to science as described here. Empirical or
factual truths seem to have been transcended, and all science seems to be in the
realm of truths of reason. One gains a similar impression from a number of other
passages in Descartes, and in the Sixth Meditation, for example, we are presented