What are philosophers trying to achieve? How can they succeed? Does philosophy make progress? Is it in competition with science, or doing something completely different, or neither? Timothy Williamson tackles some of the key questions surrounding philosophy in new and provocative ways, showing how philosophy begins in common sense curiosity, and develops through our capacity to dispute rationally with each other. Discussing philosophy's ability to clarify our thoughts, he explains why such clarification depends on the development of philosophical theories, and how those theories can be tested by imaginative thought experiments, and compared against each other by standards similar to those used in the natural and social sciences. He also shows how logical rigour can be understood as a way of enhancing the explanatory power of philosophical theories. Drawing on the history of philosophy to provide a track record of philosophical thinking's successes and failures, Williamson overturns widely held dogmas about the distinctive nature of philosophy in comparison to the sciences, demystifies its methods, and considers the future of the discipline. From thought experiments, to deduction, to theories, this little book will cause you to totally rethink what philosophy is.