This book is concerned with the role of intuitions in the justification of philosophical theory. The author begins by demonstrating how contemporary philosophers, whether engaged in case-driven analysis or seeking reflective equilibrium, rely on intuitions as evidence for their theories. The author then provides an account of the nature of philosophical intuitions and distinguishes them from other psychological states. Finally, the author defends the use of intuitions as evidence by demonstrating that arguments for skepticism about their evidential value are either self-defeating or guilty of arbitrary and unjustified partiality towards non-intuitive modes of knowledge.