Definition
Derek Parfit (1942–2017) was a British philosopher who specialized in personal identity, rationality, and ethics. He is widely considered one of the most important and influential moral philosophers of the late 20th and early 21st centuries.
Why It Matters
Parfit’s work provides the philosophical foundation for how we should think about ourselves and our responsibility to the future. His reductionist view of identity encourages a more altruistic and rational approach to global challenges like climate change and AI.
Core Concepts
- Personal Identity: Parfit challenged the notion of a fixed “self,” arguing that identity is a matter of degree based on psychological continuity and connectedness (Relation R).
- Reasons and Persons: His magnum opus, which explores the nature of rationality and morality. He argued for a “reductionist” view of persons.
- Population Ethics: He introduced the Repugnant Conclusion, a paradox in which a very large population with a very low quality of life is judged better than a smaller population with a very high quality of life.
- Effective Altruism: Parfit’s work on long-termism and the importance of future generations is a foundational pillar of the Effective Altruism movement.