Descartes: A Biography

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 Descartes: A Biography

to generations of students. This attitude of complete confidence in his

ownwork and a consistent failure to acknowledge the contributions of

others, including such luminaries as Galileo, was slightly modified in the

course of replying to objections to theEssays. Then, for the first time,

he acknowledged the indirectness of the evidence that supports scien-

tific theories, and the lack of parity between mathematical proofs and

scientific ‘demonstrations’. During,inparticular, a new phrase –

often written in Latin, for emphasis – appeared in his correspondence,

in reply to queries about scientific questions: ‘Est quaestio facti’ (that is a

factual question).Nonetheless, this explicit recognition of the need for

empirical evidence, in addition to speculative explanations, did nothing

to reduce Descartes’ confidence in the validity of his work. Nor did he

experience a crisis of confidence, an emotional collapse, or anything faintly

similar to a mental breakdown, as had been reported in the lives of other

philosophers. The explanation of this late interest in scepticism is much

simpler. Once a Latin version of theDiscoursewas in circulation, he could

no longer avoid discussing contemporary scepticism and its relevance to

metaphysical questions.

Descartes was already familiar with Jean Silhon’s bookTwo Truths,

which had been published inwhen he was still living in Paris. In

, Silhon reworked many of his earlier ideas in a new book entitledThe

Immortality of the Soul,inwhich he discussed Pyrrhonism as undermining

belief in God and the soul. However, his interest in those questions was not

purely metaphysical; he argued that the social order depends on belief in

the immortality of the soul. ‘Without it, the political order and civil society,

which flourish...bythe just relation and faithful correspondence between

the right of Sovereigns and the duty of subjects, will soon dissolve.’There

was nothing novel about these remarks in thes.What was surprising,

however, was the argument developed by Silhon to establish at least one

truth that he considered to be beyond doubt.

Here is a piece of knowledge that is certain, no matter what direction one turns it

or from what perspective one considers it, and is such that it is impossible for any

person capable of reflection and discussion to doubt and to fail to be convinced about

it. Every person, I say, who has the use of judgment and reason can knowthat they

are, that is to say, that they have a being and that this knowledge is so infallible that, if

all the operations of the external senses were deceptive in themselves, or if one could

not distinguish between them and the operations of a disturbed imagination; or if one

could not be fully convinced that one is awake or asleep and that what is seen is true