Parfit

Parfit refers to Derek Parfit (1942–2017), a British philosopher renowned for his work on personal identity, ethics, rationality, and population ethics. He spent most of his career at Oxford University, where he was a long-time fellow of All Souls College. Parfit’s writings have influenced debates across moral philosophy, philosophy of mind, and normative ethics.

In Reasons and Persons (1984), Parfit advanced the view that personal identity over time is not what matters for survival; rather, psychological continuity and connectedness are what matter. Through thought experiments such as cases of teletransportation and brain swaps, he argued that identity is less important than overlap in memories, intentions, and personality. He also introduced the non-identity problem in population ethics, examining how policy choices that affect which individuals come into existence can complicate judgments about harms and benefits.

In his later work, notably On What Matters (2011), Parfit articulated a form of moral realism and a broadly consequentialist outlook. He argued that there are objective reasons for action accessible to rational scrutiny and that there is significant overlap among moral, rational, and prudential reasons. The book surveys normative, metaethical, and rational-choice themes, emphasizing impartial benevolence and the coherence of our ethical intuitions with rationality.

Parfit’s work has had a lasting impact on contemporary philosophy. His analyses of personal identity, the non-identity problem, and the foundations of moral reasoning continue to shape discussions in ethics, philosophy of mind, and political philosophy.