Transcendental apperception and knowing that i am

In the Critique of Pure Reason, Kant makes an enigmatical assertion that in the transcendental apperception "I am conscious of myself not as I appear to myself, nor as I am in myself, but only that I am." This thesis is an analysis of this interesting existential claim which is denied to be either of phenomenon or of noumenon. In the first part of the thesis, I consider the implications of this existential claim together with the subject's necessary consciousness of himself as an identical self in apperception, which Kant claims to be a transcendental requirement for cognition to be possible. In the second part, I discuss the relation between the apperceptive I think and I exist since Kant's enigmatic existential assertion is grounded on the I think. Then, I claim that Kant's making use of the I think to show that I exist is similar to Descartes' cogito ergo sum, as what yields the knowledge that I exist is the subjective consciousness of the activity in thinking; and I appeal to Jaakko Hintikka's interpretation of cogito as performance to show this similarity between Kant's apperceptive I think and Descartes' cogito. Finally, the thesis of subjective-active intuition is presented in order to supply an explanation of the unique cognitive status that subjects have of themselves and about the epistemic nature of the knowledge of their own existence.