"There is thinking: therefore there is something that thinks": this is the upshot of all Descartes' argumentation. But that means positing as "true à priori" our belief in the concept of substance-- that when there is thought there has to be something "that thinks" is simply a formulation of our grammatical custom that adds a doer to every deed. In short, this is not merely the substantiation of a fact but a logical-metaphysical postulate--Along the lines followed by Descartes one does not come upon something absolutely certain but only upon the fact of a very strong belief.
If one reduces the proposition to "There is thinking, therefore there are thoughts," one has produced a mere tautology: and precisely that which is in question, the "reality of thought," is not touched upon--that is, in this form the "apparent reality" of thought cannot be denied. But what Descartes desired was that thought should have, not an apparent reality, but a reality in itself.
The concept of substance is a consequence of the concept of the subject: not the reverse! If we relinquish the soul, "the subject," the precondition for "substance" in general disappears. One acquires degrees of being, one loses that which has being.
Critique of "reality": where does the "more or less real," the gradation of being in which we believe, lead to?--
The degree to which we feel life and power (logic and coherence of experience) gives us our measure of "being", "reality", not appearance.
The subject: this is the term for our belief in a unity underlying all the different impulses of the highest feeling of reality: we understand this belief as the effect of one cause--we believe so firmly in our belief that for its sake we imagine "truth", "reality", substantiality in general.-- "The subject" is the fiction that many similar states in us are the effect of one substratum: but it is we who first created the "similarity" of these states; our adjusting them and making them similar is the fact, not their similarity (--which ought rather to be denied--).
One would have to know what being is, in order to decide whether this or that is real (e.g., "the facts of consciousness"); in the same way, what certainty is, what knowledge is, and the like.-- But since we do not know this, a critique of the faculty of knowledge is senseless: how should a tool be able to criticize itself when it can use only itself for the critique? It cannot even define itself!
