Reasons and Persons
Derek Parfit was a fellow at All Souls College, Oxford, and Reasons and Persons is the book that built his reputation. He works through four long sections, arguing against the rationality of pure self-interest, then dismantling the common view that personal identity is what matters in survival, and finally turning to the moral problems raised by future people and population size. Parfit invents thought experiments about teletransportation, branch-line cases, and the non-identity problem that have become standard reference points in ethics and philosophy of mind. The book is famously dense, but it changed how academic philosophers think about identity, rationality, and our duties to people who do not yet exist. It remains the central text behind the field now called population ethics.
What you might want to know about Reasons and Persons
The questions readers send us most often, answered without spoilers.
Derek Parfit attacks self-interest theory, the metaphysics of personal identity, and our obligations to future generations in one of the most influential works of late twentieth-century philosophy.
Harris has repeatedly called Derek Parfit an alien intelligence and pointed readers to Reasons and Persons as one of the most important philosophy books of the last century, especially on personal identity.
Not really. It assumes comfort with analytic argument, so most readers come to it after some background in ethics or philosophy of mind.
Reasons and Persons was written by Derek Parfit, published in 1984 by Oxford University Press.
Reasons and Persons is 560 pages in standard print editions, though page counts vary slightly between hardcover, paperback, and large-print formats.
At an average reading pace of about 250 words per minute, Reasons and Persons takes most readers 8 to 12 hours to finish.
Reasons and Persons is available in hardcover, paperback, ebook, and audiobook formats from Amazon, Bookshop.org, ThriftBooks, and most major bookstores.