This paper discusses the main criticism launched against legal monism and the Pure Theory of Law, as envisaged by Hans Kelsen and the other proponents of the Vienna School of Jurisprudence, namely the criticism voiced by two of the most eminent legal theorists, HLA Hart and Joseph Raz. According to them, legal monism fails to offer a satisfactory theory of the identity of legal systems and it therefore simply cannot be considered a viable theory of legal systems, because it leads (...) to obviously absurd consequences. These arguments which take the form of an attack on the most basic tenets of the Pure Theory of Law and thus legal monism, will be duly addressed and consequently rebutted in this paper, particularly in order to be able to maintain legal monism in its juridico-epistemological manifestation as a working and viable theory of the law. (shrink)