This paper offers a diachronic reconstruction of MacCormick's theory of law and legal argumentation: In particular, two related points will be highlighted in which the difference between the perspective upheld in Legal Reasoning and Legal Theory and the later writings is particularly marked. The first point concerns MacCormick's gradual break with legal positivism, and more specifically the thesis that the implicit pretension to justice of law proves legal positivism false in all its different versions. The second point concerns MacCormick's acceptance (...) of the one-right-answer thesis and the consequent thinning of the differences between MacCormick's theory of legal reasoning and that of Ronald Dworkin and of Robert Alexy. The intent, however, is not only to describe this change in MacCormick's thought, but also to attempt a defence of the original view that we find in Legal Reasoning and Legal Theory. (shrink)