According to Kant, the division of the categories “is not the result of a search after pure concepts undertaken at haphazard,” but is derived from the “complete” classification of judgments developed by traditional logic. However, the sorts of judgments that he enumerates in his table of judgments are not all ones that traditional logic has dealt with; consequently, we must say that he chose the sorts of judgments in question with a certain intention. Besides, we know that his choice of (...) judgments and categories is strongly influenced by certain views of natural science that he fully accepts. For this reason, his argumentations are sometimes seriously inconsistent. As to Kant’s argumentations of categories, many problems have already been pointed out, but in this paper, I take up the categories of quantity and quality once more, and make clear his argumentations’ hidden logic and its distortion from the point of view of the history of logic and natural science. First, I confirm that there are non-negligible problems in his explanation to the effect that his derivation of the categories of quantity and quality is based on the quantity and quality of judgments. Next, I reconsider the meaning of his treating the categories of quantity and quality as pure concepts of the understanding. Finally, I conclude that by having recourse to the categories of quantity and quality Kant tried unjustly to apriorize the distinction between the “extensive magnitude” and “intensive magnitude” that has a long formational history since Aristotle. (shrink)