What if the premise of CPR's Transcedental Deduction is wrong?

Question

The transcendental unity of apperception is that unity through which all the manifold given in an intuition is united in a concept of the object. It is therefore entitled objective, and must be distinguished from the subjective unity of consciousness… Whether I can become empirically conscious of the manifold as simultaneous or as successive depends on circumstances and empirical conditions. Therefore, the empirical unity of consciousness, through association of representations, itself concerns an appearance, and is wholly contingent… Only the original unity is objectively valid: the empirical unity of apperception,… which… is merely derived from the former under given conditions in concreto, has only subjective validity. One person connects the representation of a certain word with one thing, the other [person] with another thing; the unity of consciousness in that which is empirical is not, as regards what is given, necessarily and universally valid. (B139–40)

It seems to me that the premise of Transcendental Deduction lies on the fact that for a representation to be objectively valid it must be a representation of an objective feature of reality.

In this section Kant says that our experience must be universally valid [Premise]. He then proves (I agree with him here), that Hume's theory of associations cannot preserve the universal validity of our experience since impressions can only be contingent. Thus, another theory is needed to 'link' the manifold of representations together to achieve this empirical unity. For this reason, an a priori faculty of understanding is posited as 'necessary' and 'sufficient'.

What if the Premise is wrong? What if we do not have universally valid experience at all? Is Kant in anyway able to disprove that nothing is universally valid or does he take this premise for granted? Moreover, I do agree that he does posit that for empirical unity of consciousness, a transcendental unity of apperception is required (for self-identity throughout my representations). However, it still doesn't establish the usage of understanding, but merely the existence of non-intuitive transcendental Self.

As a Foucauldian perhaps, I can just accuse him of being an 'enlightenment' warrior. He takes objectiveness of truth for granted.

Answer 1

The B-Deduction is very explicit about the fact that the argument descends from a given premise of the unity of apperception. It is however incorrect to interpret this premise as asserting, as you call it, "the objective validity of experience". This is, in some sense, what is to be proved, as far as its the categories which give objective validity to experience. It's more appropriate to say that the assumption of the Deduction is that we have an unified self-consciousness in time.

What the Deduction establishes is that, inasfar as contents of our perception are to be reflected upon, and thus become contents of our apperception, i.e. objects of our inner sense, or, in other words, as far as they're to be considered ours, the categories have objective validity. The argument is normative in its conclusion, because it doesn't establish the actuality, anywhere in the future, of a comprehensive system of nature structured according to the categories. It simply shows that the assumption of the possibility of such a system is implicitly contained in our ability to project our self-consciousness into the future (I will not elaborate on how here, since the question isn't concerned with this).

What if the premise is wrong? I think it was Fichte who for the first time recognized the distinctively normative character of many of Kant's arguments. He said, based on this observation, that Kantian idealism, which he took to be also his own idealism, is the philosophy of freedom, i.e. of action. As long as one assumes a contemplative conception of knowledge, one can put many assumptions like the unity of self-consciousness into doubt. But, Fichte would say, it is of course nonsense, if we recognize our own agency, to doubt that. In this sense, then, all philosophy that doesn't degenerate into skepticism or dogmatism, according to Fichte, must begin from an act, a practical choice to self-reflect and recognize one's freedom. I am remained unconvinced whether this is so, but I think Fichte is onto something important here.