Descartes teached that because he thinks therefor he is. But did he tell something about the question whether there are gaps between thoughts? So probably we could not exist between those gaps? Or wasn't it possible not to think or was thinking just a quality a human posesses?

2 Answers 2


He doesn't exist because he thinks; rather, thinking is sure evidence of his existence. Sleeping, for example, is not a gap in one's existence, but a gap of being conscious of one's existence. Notice how Descartes himself speaks of it:

"Let us pass, then, to the attributes of the soul. The first mentioned were the powers of nutrition and walking; but, if it be true that I have no body, it is true likewise that I am capable neither of walking nor of being nourished. Perception is another attribute of the soul; but perception too is impossible without the body; besides, I have frequently, during sleep, believed that I perceived objects which I afterward observed I did not in reality perceive. Thinking is another attribute of the soul; and here I discover what properly belongs to myself. This alone is inseparable from me. I am--I exist: this is certain; but how often? As often as I think; for perhaps it would even happen, if I should wholly cease to think, that I should at the same time altogether cease to be. I now admit nothing that is not necessarily true. I am therefore, precisely speaking, only a thinking thing, that is, a mind (mens sive animus), understanding, or reason, terms whose signification was before unknown to me. I am, however, a real thing, and really existent; but what thing? The answer was, a thinking thing." (Meditation I)

Notice that he speaks of "wholly [ceasing] to think" instead of just a lapse in consciousness.


First of all to clarify Pé de Leão point:

I think therefore I am doesn't mean that Descarte thinks that thinking and existing are the same thing. Descartes sees thinking as proof that the mind is different from the body. So "I think therefore I am" should be interpreted as "My thinking is proof that my mind is different than my body (I think), therefore my mind has a separate existence from my body (I am)".

That being said, the fact that there are gaps between thoughts does present a problem for Descartes. One of his main arguments for the difference between mind and body is that the body is divisible, while the mind isn't (The argument from indivisibility):

"the body, by its very nature, is something divisible, whereas the mind is plainly indivisible…[This] consideration alone would suffice to teach me that the mind is wholly different from the body" (Descartes, Meditations on First Philosophy - Meditation VI).

In the synopsis of his meditations, he writes:

"we cannot conceive of half a soul, as we can in the case of any body, however small."

Locke and Hume both criticized the indivisibility argument, see the IEP article on the topic. From their point of view, thoughts are divisible, so either a different basis has to be found for why mind and body are different (Locke), or there is no difference between them (Hume). Hume in particular subscribed to the bundle theory of self, the mind is just an illusion constituted by the collection of memories and sensations that a person experiences.

On the other hand, one can argue that this criticism of Descartes is unfair, since although divisible in time, thoughts are not divisible in space the way bodies are, and that might be what he was alluding to in his indivisibility argument.

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    You'll like this one:"It thinks: but to say the “it” is just the famous old “I” — well that is just an assumption or opinion, to put it mildly, and by no means an “immediate certainty.” In fact, there is already too much packed into the “it thinks”: even the “it” contains an interpretation of the process, and does not belong to the process itself". Guess who :-)
    – Conifold
    Commented Apr 14, 2016 at 0:14
  • I never knew that N dabbled in Phil. mind. One would think that it would be "too last men" for him. Commented Apr 14, 2016 at 20:39
  • He was a Kantian before he wasn't, this one is from Beyond Good and Evil, a mature view, but the critique of cogito is close to Kant's, although much crisper. What surprised me more is that his conversion turned him from free will libertarian into a compatibilist. That's from the champion of will to power, go figure!
    – Conifold
    Commented Apr 16, 2016 at 19:41

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