Steven Burgess

Central to Descartes’ philosophy is a view about immutable essences and eternal truths. After mentioning a Platonist account of recollection in Meditation V, Descartes declares that the ideas we have of mathematical notions “are not my invention but have their own true and immutable natures” (AT VII, 64/CSM II, 44).Descartes claims that other important philosophical notions, such as God, mind, body, and human free will (AT VII, 68; AT VIII-2, 348; AT III, 383; AT VII, 433, respectively), also have immutable natures or essences. Although Descartes says a good many things about this view, nowhere does he offer definitive doctrine on the matter, and in fact frequently confuses his reader with apparently inconsistent pronouncements about immutable natures and eternal truths. In this essay, I focus on the immutable natures and propose a solution to two of the main problems associated with Descartes’ position, the metaphysical status of immutable natures and the purported indivisibility of their existence as ideas in the mind.

The question of what Descartes did and did not doubt in the Meditations has received a significant amount of scholarly attention in recent years. The process of doubt in Meditation I gives one the impression of a rather extreme form of skepticism, while the responses Descartes offers in the Objections and Replies make it clear that there is in fact a whole background of presuppositions that are never doubted, including many that are never even entertained as possible candidates of doubt. This paper resolves the question of this undoubted background of rationality by taking seriously Descartes’ claim that he is carrying out demonstrations modeled after the great geometers. The rational order of geometrical demonstration demands that we first clear away previous demonstrations not proven with the certainty necessary for genuine science. This is accomplished by the method of doubt, which is only applied to the results of possible demonstrations. What cannot be doubted are the very concepts and principles employed in carrying out geometrical demonstration, which enable it to take place. It would be senseless to ask whether we can doubt the essential components of the structure through which questioning, doubting, and demonstration are made possible.