The key to the normativist dimension of the Pure Theory, particularly in Kelsen's writings of the 1920s and early 1930s, is a Kantian argument. To set the stage for the argument, I trace, in Part I, Kelsen's steps as he constructs and then resolves what I shall call the jurisprudential antinomy. The antinomy represents, to be sure, not arestatement of an argument expressly developed by Kelsen but, rather, my interpretation of his strategy. I offer the antinomy as a means of highlighting those theses in Kelsen's Pure Theory that distinguish it from both traditional naturallaw theory and traditionallegal positivism, and as a means of pinpointing what Kelsen would have to show to make a case on behalf of his ostensibly distinct theory, amiddIe way between the traditional theories.