This chapter describes a philosophical approach to theorizing justice, mapping out some main strands of the tradition leading up to contemporary political philosophy. We first briefly discuss what distinguishes a philosophical approach to justice from other possible approaches to justice, by explaining the normative focus of philosophical theories of justice – that is, a focus on questions not about how things actually are, but about how things ought to be. Next, we explain what sorts of methods philosophers use to justify theories of justice. Following this, in the longest section, we highlight major questions about justice that have drawn the attention of philosophers, and indicate how competing conceptions of justice have arisen from differing answers to these questions. The goal here is not to answer but to elucidate some of the larger questions about justice, as well as to establish a framework for understanding and distinguishing different kinds of claims about justice and some of the relations between them.