The task of this work is explaining why Kant claims in Critique of Pure Reason that infinite judgments of the form S is not-P are not reducible to the affirmative ones of the form S is P nor to the negative ones of the form S is not P The distinction does not seem justifiable in the extensional approach that is proper of General Logic, since the equivalence between infinite and negative judgments ends up to be inevitable. We adopt a method that is suggested by Kant s advices, which consists in looking for some moment in the discussion of Transcendental Dialectic where this form of judgment plays an exclusive and indispensable role. Two hypotheses are examined. The first one is that infinite judgments have an essential role in the formulation and in the solution of the First Antinomy of Pure Reason. The second one is that they have function in the formulation of the Principle of Complete Determination, which is mentioned in order to explain the Transcendental Ideal of Pure Reason. Actually, this second hypothesis will show up as the solution for our problem, but also will have strong repercussions at the interpretation of the whole Critique of Pure Reason, especially for presupposing an intensional aspect of predication that generally has been ignored and sometimes denied by Kantian philosophy s commentators.