Cogito: The First Certainty

In Meditations II Descartes argues that even if the Evil Demon is deceiving him about everything else, it cannot be deceiving him about one thing - that he exists. As long as he is doubting everything, he is thinking, and as long as he is thinking, he must exist. Cogito, ergo sum. I think, therefore I am; or: I am thinking, therefore I exist. If the demon tricked him into thinking he didn't really exist, he could reason his way out of the trickery, for if he is doubting his own existence, he is surely thinking. Something is thinking, and that which thinks is the "I".

Clearly, Descartes is making the assumption that thoughts require a subject to think them, something that isn't itself a thought but which in some sense is aware of the thoughts. Is he entitled to assume that thoughts require a thinker? If we think he isn't then his argument fails, for all he'd be left with is "There are thoughts". In any case, he does seem to be assuming that the subject of the thoughts is a continuing thing, subsisting from one thought to the next, and from one kind of mental process to the next (doubting, imagining, etc). He is not entitled to do this, for this could be an illusion created by the demon. But without this continuing "I", his argument looks much weaker: a fleeting "I" that exists only momentarily, as each separate thought occurs, would not be able to reason. It could not form the cogito argument, nor be the subject of clear and distinct ideas, for it would not be able to linger on them long enough to check they really are clear and distinct.

Perhaps you disagree with me, or have your own arguments against Descartes. Get posting!