Risk has become one of the main topics in fields as diverse as engineering, medicine and economics, and it is also studied by social scientists and psychologists. But the topic of Risk also leads to more fundamental questions such as: What is Risk? What can decision theory contribute to the analysis of Risk? What does the human perception of Risk mean for society? How van we judge whether a Risk is morally acceptable or not? Over the last couple of decades questions like these have attract interest from philosophers into the theory of Risk. The Handbook of Risk Theory provides the reader with a state of the art overview of the epistemological, decision theoretical, ethical and social aspects of Risk. This is the first handbook on Risk Theory that is written from a philosophical perspective, while addressing a general, interdisciplinary audience of Risk scholars. All contributors are key figures in their field, who at the same time have experience in working together with natural scientists, engineers, medical scholars, economist and social scientists. For this reason all contributions are accessibly written and highly relevant to issues that are studies by Risk scholars. This makes the Handbook of Risk Theory the perfect starting point for all Risk scholars who are interested in broadening and deepening their current perspectives.