Inconsistencies have been the object of study of numerous analytical legal philosophers like H. L. A. Hart, Hans Kelsen, Alf Ross, Norberto Bobbio, Lon Fuller, Ronald Dworkin, Carlos Alchourrón, Eugenio Bulygin, and Pierluigi Chiassoni. Although these authors hold differing views on inconsistencies, I argue that they have all failed to arrive at a sound taxonomy of the different types of inconsistencies that can occur in the law. I claim that inconsistencies can be classified into two types, namely, contradictions and conflicts. I also contend that inconsistencies are not to be confused with improper inconsistencies, which do not concern instances of logical incompatibility between norms, but rather of functional incompatibility between them, which means that the application of one norm undermines the achievement of the goals or purposes pursued by another norm. The central claim of this dissertation is that a failure to differentiate between contradictions and conflicts as two types of inconsistencies as well as a failure to differentiate between inconsistencies and improper inconsistencies has often resulted in mistaken views about how inconsistencies affect the law’s ability to provide guidance and of how problems arising from inconsistencies in the law can be remedied. I examine the Validity Thesis (inconsistent norms can be simultaneously valid in a single legal system), the Guidance Thesis (inconsistencies undermine law’s ability to offer guidance to individuals’ conduct by rendering the law indeterminate), the Interpretation-Creation Thesis (inconsistencies are created by interpretation) and the Modification of the Law Thesis (the resolution of inconsistencies entails a modification of the legal system) with the purpose of showing how they are to be understood or, more precisely, what interpretation is to be given to them to make them correct.