although mediaeval thought had already been slumbering for two centuries when Descartes began to write, he was the first to build up a new system of ideas and to open formally a new philosophical era. His predecessors had done little more than to distrust scholastic philosophy, and, as they knew no other one, to extend their distrust to philosophy itself. Descartes brought to the world the unexpected revelation that, even after the breakdown of mediaeval philosophy, constructive philosophical thinking was still possible. Ever since the fourteenth century there had been men to criticize Aristotle, but Descartes' ambition was quite different: it was to replace him.In the next paragraph, Gilson says that Descartes marks the transition from the Renaissance, rather than from the Middle Ages, to the modern world. He qualifies the statement by noting that Descartes does not mark the transition from the whole Renaissance to the modern world, “but, quite exactly, from the scepticism of Montaigne to the modern period of constructive thinking in philosophy.” He says that Cartesianism was a direct answer to the challenge of Montaigne’s scepticism.
Gilson goes on to explain the connection between Descartes’s Discourse on Method and Montaigne’s Essays:
The long list of passages of the Discourse on Method that are but an echo of the Essays, clearly shows how conversant Descartes was with the work of Montaigne. What can be more modern, for instance, than the opening sentence of the Discourse? "Good sense is of all things in the world the most equally distributed, for everybody thinks himself so abundantly provided with it, that even those most difficult to please in all other matters do not commonly desire more of it than they already possess." Was not this the first article of the charter of independent thought? If, as Descartes immediately added, good sense, or reason "is, by nature, equal in all men" why should it ever submit to authority? True, but the fact remains that the first lines of the Discourse are borrowed from Montaigne's essay On Presumption (Essays, Bk. II, Chap. 17) : "of all the gifts made to man by Nature, the most justly distributed is judgment (or sense), for no man is ever displeased with what amount of it he may have received." I quite agree that Descartes read his own thought into the text of Montaigne, but rather than an objection to my thesis, it is the very point I hope to make: the philosophy of Descartes was a desperate struggle to emerge from Montaigne's scepticism and the very form of the Discourse on Method is enough to suggest it.Descartes was a skeptic, because it was the fashion of his time to be a sceptic, but he was skeptic who was looking for something better than scepticism. Gilson says that Descartes’s scepticism amounts to a kind of Mathematicism (a philosophy that progresses by the method of mathematics).