Descartes' Cogito and Kant's Transcendental Deduction of the Categories

In Kant's deduction of the categories, he shows that two things are the same which usually are spoken of as different: the a priori unity of our representations is the same thing as the unity of consciousness. To put this in other terms which are more understandable: relationships thought between objects are at the same time the subject ('I') in its pure form. If we consider Descartes' Cogito along the lines of Kant's deduction, we find greater insight into how Descartes' Ego Cogito should be understood.

Ego Cogito, Ego Sum. These words, which do not constitute an argument so much as a recognition, seemed to change the course of Philosophy after them. When we look at what cognitions compose Descartes' Ego, he first describes a laundry list of thought processes: doubts, understanding, affirmation, denial, will, imagination and sensory perception. If we want to consider all of these as related to Kant's deduction we will concern ourselves with sensory perception.

We can note that the other sorts of cognition other than sensory perception all concern sensory perception directly or indirectly. We understand what is given through sense, and our judgments consist in connecting that understanding to doubt, affirmation, denial, willing (an act in the sensory world) or being unwilling (in the sensory world); Descartes' exploration of the kinds of ideas that we have to imagine with also shows that they all either come from sense originally or are innate.

Now, Descartes says, "Ego Cogito, Ego Sum": I think, I am. These statements are equivalent (there is no 'therefore'). If we concern ourselves with just sensory perception, we can say, "I perceive, I am", as an accurate reformulation. Now, it is very easy to see this as saying, like Kant, that the unity of representations is also the unity of consciousness (what is taken to be 'I'). There is just one concern that may bother us: Descartes speaks of himself as if he is a substance, which gives the impression that there is something underlying the thought, or which thought adheres to as a predicate.

Kant is clear about avoiding the pitfalls that Descartes gets accused of. He notes that we cannot attribute substance to the subject, since substance only applies to objects, but in its application to objects the subject is produced as well. This use of 'substance' in Kant is incredibly refined, since it not only has the general characteristic meaning of substance (something which is only predicated of, and not a predicate), but also additional refinements in terms of how the concept is able to be used by us.

The refinements in the use of 'substance' in Kant may be a large change in the sense of the word such that if we look back at Descartes we can find that substance might be used in a different way. It's clear that Descartes does not intend for the substance to be understood in terms of a material, and it seems like it would be much easier to understand it in terms of an idea. There is also reason to think that Descartes really only considered God a substance.

Even if we can not completely clear Descartes' name of all faults (though I may attempt it), we can still get greater insight into his work by clarifying elements of it through such comparisons as above.