What makes a biological entity an individual? Jack Wilson shows that past philosophers have failed to explicate the conditions an entity must satisfy to be a living individual. He explores the reason for this failure and explains why we should limit ourselves to examples involving real organisms rather than thought experiments. This book explores and resolves paradoxes that arise when one applies past notions of individuality to biological examples beyond the conventional range and presents an analysis of identity and persistence. The book's main purpose is to bring together two lines of research, theoretical biology and metaphysics, which have dealt with the same subject in isolation from one another. Wilson explains an alternative theory about biological individuality which solves problems which cannot be addressed by either field alone. He presents a more fine-grained vocabulary of individuation based on diverse kinds of living things, allowing him to clarify previously muddled disputes about individuality in biology. – Contents : Acknowledgements. – Part I. Beyond Horses and Oak Trees: A New Theory of Individuation for Living Entities: – 1. Introduction; – 2. The meaning of 'a life'; – 3. The poverty of examples; – 4. Imaginary examples and conceptual analysis; – 5. What is it?. – Part II. The Biological and Philosophical Roots of Individuality: – 6. Why biologists (should) care about individuality; – 7. Philosophers on living entities; – 8. Natural kinds and substantial kinds; – 9. Patterns and natural kinds. – Part III. Individuality and Equivocation: – 10. Paradigm individuals: the higher animals; – 11. Other possible solutions; – 12. The proposed solution. – Part IV. The Necessity of Biological Origin and Substantial Kinds: – 13. A valid argument for sortal essentialism; – 14. The necessity of biological origin; – 15. Sex; – 16. Species membership and the necessity of genealogy. – Part V. Generation and Corruption: – 17. Genetic individuals; – 18. Functional individuals; – 19. Developmental individuals; – 20. Raising the dead. – Part VI. Personal Identity Naturalized: Our Bodies, Our Selves: – 21. Human beings as biological entities; – 22. Is a person a human being?; –23. Conclusions. – Appendix. Identity and sortals: why relative identity is self-contradictory; – Includes bibliographical references (p. 131-134) and index.