Summary: Meditations on First Philosophy

Is there any truth that is absolutely certain?

It is to this question that Descartes seeks an answer in the Meditations on First Philosophy.

He observes that the senses can deceive us and that, for this reason, it is wise not to trust those who have misled us even once.

He revisits the sceptical arguments: a square tower appears round from a distance, a stick submerged in water looks broken, and so on.

Certainly, doubting the existence or truth of the external world may seem extreme. However, we must not forget that when we dream, we firmly believe in the reality of what we perceive, even though it is merely an illusion. Could we be living in a dream, in which nothing truly exists?

Descartes responds that imagination has its limits: it cannot create entirely new things but only recombine existing elements in different ways. Therefore, it is unlikely that our world is purely a product of imagination.

Descartes proposes a distinction between the sciences of composite things (physics, medicine), which are doubtful because they deal with objects that imagination could have fabricated through arbitrary combinations, and the sciences of simple things (arithmetic, geometry, etc.), which concern extension, shapes, quantities, space, and time, and which, in themselves, seem certain. For whether I am awake or asleep, two and three joined together will always make five ¹.

However, the author of the Meditations on First Philosophy ultimately rejects even this distinction: what if God deceives us even in these matters? Does God's goodness not rule out such a possibility? How could he deceive us in this way?

In reality, even the existence of God is uncertain. Once again, we find ourselves in profound doubt.

Descartes then imagines the most extreme hypothesis: that of the evil demon:

A certain evil demon, no less cunning and deceitful than powerful, has employed all his industry in deceiving me ².

This hypothesis, which concludes Book I, is revisited at the beginning of Book II. Descartes is still searching for an indubitable truth, just as Archimedes sought a fixed point from which to move the Earth.

Indeed, at the very heart of the most radical doubt—the hypothesis of the evil demon—lies a certain truth: There is therefore no doubt that I am, if he deceives me ³.

So we see here the emergence of what is known as the Cartesian cogito:

So that, having thought it through, we must conclude and hold it to be constant that this proposition: ‘I am, I exist’ is necessarily true whenever I utter it or conceive it in my mind ⁴.

In the Discourse on Method, Descartes expressed this more succinctly: I think, therefore I am.

Thus, at the very core of doubt, a certain truth is revealed. But does it conceal others?

Descartes seeks to derive further indubitable truths from it.

Can anything certain be said about this thinking self? What is the "I" of "I think"?

Am I a man? Am I a soul? These vague terms cannot be retained without further examination. What is a man? A rational animal, as defined by Aristotle and the Scholastics? What is a soul? Could I not be more than just a soul—also a body?

In fact, we must return to the indubitable truth of "I think". All that can be stated with certainty about myself is that I am, strictly speaking, nothing but a thinking thing ⁵.

From this essential attribute—thought—it follows that we can affirm a range of other truths about the self:

What is a thinking thing? It is a thing that doubts, understands, conceives, affirms, denies, wills, does not will, also imagines, and perceives ⁶.

Thus, from the cogito, step by step, we deduce a series of certain truths.

¹ Méditations métaphysiques, GF Flammarion, Paris, 2009, p.85
² p.89
³ Ibid.
⁴ Ibid.
⁵ p.97
⁶ p.99