Philosophers have always recognized the value of reason, but the process of reasoning itself has only recently begun to emerge as a philosophical topic in its own right. Is reasoning a distinctive kind of mental process? If so, what is its nature? How does reasoning differ from merely freely associating thoughts? What is the relationship between reasoning about what to believe and reasoning about how to act? Is reasoning itself something you do, or something that happens to you? And what is the value of reasoning? Are there rules for good or correct reasoning and, if so, what are they like? Does good reasoning always lead to justified belief or rational action? Is there more than one way to reason correctly from your evidence? This volume comprises twelve new essays by leading researchers in the philosophy of reasoning that together address these questions and many more, and explore the connections between them.