The deduction of the categories lies undoubtedly at the very heart of Kant's theoretical philosophy and, for this reason, it is one of items in the philosophical canon that is greatly discussed and least agreed upon. In the modern and contemporary Western philosophical tradition as well as in Kant’s literature, the loci classici for its consideration are the 1781 and 1787 editions of the Critique of pure reason. In this paper, I aim at presenting and discussing an argument that Kant (...) advances in the Prolegomena and which is virtually ignored in the approach of the deduction of the categories. At first, an inquiry into the distinction between analytic and synthetic methods is carried out. After that, the difference between judgments of perception and judgments of experience is taken into account. Finally, the Prolegomena’s argument for the categories is brought into discussion. (shrink)