This article intends to carry out an approach to modern legal thought, for them, initially performing a legal positivist approach, its most significant expression and criticism and its most important conceptual aspects from its origins, (ii) then try to specify in that is what has been called the crisis of positivism and discussion of the occasion arises between positivists and anti-positivist, and finally (iii) makes significant criticisms to the central theses of legal positivism. In developing the above attempt to account for the five central problems that have been the focus of the debate between positivists and anti-positivist in its order are: (i) the problem of obedience and the validity of law; (ii) the problem of judicial discretion and the creation of law; (iii) the issue of correction of law; (iv) the problem of conceptualization of legal positivism; (v) the issue of inclusion of morality in law.