The book "What Is Disease?" offers a comprehensive exploration of the fundamental concepts of illness and health, presented by esteemed philosophers and medical ethicists. At its core is a critical analysis of the definition of disease as a value-free scientific concept, as articulated by Christopher Boorse. Boorse addresses the criticism of his viewpoint, known as naturalism or neutralism, and updates his significant ideas on this central topic. Furthermore, other prominent thinkers illuminate alternative, non-naturalistic theories of disease and their relevance to current bioethical issues. This book is a valuable resource for anyone looking to engage with the complex and often contentious definitions of disease.