Book excerpt: In Explaining Cancer, Anya Plutynski addresses a variety of philosophical questions that arise in the context of cancer science and medicine. She begins with the following concerns: · How do scientists classify cancer? Do these classifications reflect nature's "joints"? · How do cancer scientists identify and classify early stage cancers? · What does it mean to say that cancer is a "genetic" disease? What role do genes play in "mechanisms for" cancer? · What are the most important environmental causes of cancer, and how do epidemiologists investigate these causes? · How exactly has our evolutionary history made us vulnerable to cancer? Explaining Cancer uses these questions as an entrée into a family of philosophical debates. It uses case studies of scientific practice to reframe philosophical debates about natural classification in science and medicine, the problem of drawing the line between disease and health, mechanistic reasoning in science, pragmatics and evidence, the roles of models and modeling in science, and the nature of scientific explanation.