What is Descartes' "Cogito", and what, if anything does it prove?

University Degree Historical and Philosophical studies

What is Descartes’ “Cogito”, and what, if anything does it prove?

In his Meditations Descartes is using a method of doubt intended to eliminate any uncertainty about the world and himself. He tried to establish something ‘firm and durable in the sciences’ putting aside all of the beliefs acquired in the course of his life. Descartes’ argument can be outlined as follows: Suppose our senses lie to me about everything that I see around me. So, I can doubt the existence of my body, the sea, the sky, etc. But I can only doubt if I exist, because doubting, as a thought requires a thinker. I think, therefore I am. As Descartes summed up his argument in Latin: ‘Cogito, ergo sum’.

The argument that Descartes is representing cannot be a valid argument:

I think

I am.

Here we can substitute the act of thinking for any other act, such as walking, or breathing. If we tried to attack Descartes by a similar argument, for example: ‘Respiro ergo sum’ (‘I am breathing therefore I am’) his reply would probably be that we cannot know if the presupposition is true since breathing indeed presumes the existence of a body which we doubt. In order for the above argument to be valid we need to add another premise:

I think.

Anything that thinks exists.

I exist.

If we rely on Burman, whose notes are quoted by Williams, Descartes did admit that the suppressed premise ‘anything that thinks exists’ is ‘presupposed by the cogito’. But now we can doubt this premise: ‘Anything that thinks exists’. Would an Artificial Intelligence computer exist if it thought to itself that it existed? Or, on the contrary, would those with some kind of a serious brain damage that would not allow them to think, not exist?

At this point we can say that just as there are reasons for ...