This work is, in the words of Luigi Ferrajoli, "for many years a classic of philosophy of law. It is perhaps the best known and read "legal philosophy book Norberto Bobbio. Therefore continues Ferrajoli not only provides "basic coordinates and categories of philosophical reflection on law" but also "a way of thinking and research oriented conceptual analysis, clarity in language, the rigor and distinctions rational approach to problems. "
The first part presents Bobbio his conception of the philosophy of law, distinguishing tasks, analyzing problems and proposing a program of ius-philosophical work aimed at clarifying concepts, dissolve false disputes and promote the exchange of ideas, against all forms of dogmatism, between different philosophical orientations.
In the other two parts of the book the author returns to the secular dispute between natural law and legal positivism. Putting, as he says, "in the role of arbitrator or, more modestly, of investigating judge, rather than the defender or prosecutor," but actually defending the second against the first, an analysis of the terms, the meaning and different levels that usually presents this alternative.
By distinguishing the different meanings of legal positivism, as avalorativa method or approach to the study of positive law, as statist theory of law and ideology ethical legalista- it shows how much confusion favors radical criticism as the unconditional defense of legal positivism, one and other unjustified. And by subjecting the natural law doctrines analysis, shows that they all consist of objectivist doctrines of morality, as unfounded opinion, even recognizing its historic role as an ethical-political doctrines aimed at criticism of the existing law and design right future.