Derek Parfit

Derek Antony Parfit (; 11 December 1942 – 2 January 2017 ) was a British philosopher who specialised 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.

Early life and education Parfit was born in 1942 in Chengdu, China, the son of Jessie (née Browne) and Norman Parfit, medical doctors who had moved to Western China to teach preventive medicine in missionary hospitals. The family returned to the United Kingdom about a year after Parfit was born, settling in Oxford. Parfit was educated at the Dragon School and Eton College, where he was nearly always at the top of the regular rankings in every subject except mathematics. From an early age, he endeavoured to become a poet, but he gave up poetry towards the end of his adolescence.

He then studied modern history at Balliol College, Oxford, graduating in 1964. In 1965–66, he was a Harkness Fellow and took courses at The New School, New York University, Columbia University, and Harvard University. During these years, he met, among others, John Rawls, Stuart Hampshire, and Robert Paul Wolff.

Career After his Harkness Fellowship, Parfit returned to Oxford to start his BPhil in philosophy, and became a fellow of All Souls College. He held this position until age 67, at which point university policy mandates retirement. He remained a regular visiting professor at Harvard, New York University, and Rutgers.

Parfit contended that to be indirectly individually self-defeating and directly collectively self-defeating is not fatally damaging for S. To further bury self-interest, he exploited its partial relativity, juxtaposing temporally neutral demands against agent-centred demands. The appeal to full relativity raises the question whether a theory can be consistently neutral in one sphere of actualisation but entirely partial in another. Stripped of its commonly accepted shrouds of plausibility that can be shown to be inconsistent, self-interest can be judged on its own merits. While Parfit did not offer an argument to dismiss S outright, his exposition lays self-interest bare and allows its own failings to show through. It is defensible, but the defender must bite so many bullets that they might lose their credibility in the process. Thus a new theory of rationality is necessary. Parfit offered the "critical present aim theory", a broad catch-all that can be formulated to accommodate any competing theory. He constructed critical present aim to exclude self-interest as our overriding rational concern and to allow the time of action to become critically important. But he left open whether it should include "to avoid acting wrongly" as our highest concern. Such an inclusion would pave the way for ethics. Henry Sidgwick longed for the fusion of ethics and rationality, and while Parfit admitted that many would avoid acting irrationally more ardently than acting immorally, he could not construct an argument that adequately united the two.

Where self-interest puts too much emphasis on the separateness of persons, consequentialism fails to recognise the importance of bonds and emotional responses that come from allowing some people privileged positions in one's life. If we were all pure do-gooders, perhaps following Sidgwick, that would not constitute the outcome that would maximise happiness. It would be better if a small percentage of the population were pure do-gooders, but others acted out of love, etc. Thus consequentialism too makes demands of agents that it initially deemed immoral; it fails not on its own terms, for it still demands the outcome that maximises total happiness, but does demand that each agent not always act as an impartial happiness promoter. Consequentialism thus needs to be revised as well.

Self-interest and consequentialism fail indirectly, while common-sense morality is directly collectively self-defeating. (So is self-interest, but self-interest is an individual theory.) Parfit showed, using interesting examples and borrowing from Nashian games, that it would often be better for us all if we did not put the welfare of our loved ones before all else. For example, we should care not only about our own children, but everyone's children.

On What Matters

In his second book, Parfit argues for moral realism, insisting that moral questions have true and false answers. Further, he suggests that three categories of ethical theory—Kantian deontology, consequentalism, and contractualism—converge on the same answers to moral questions.

In the conclusion of the third volume, published shortly after his death, Parfit writes that the affluent have strong moral obligations to the poor:

One thing that greatly matters is the failure of we rich people to prevent, as we so easily could, much of the suffering and many of the early deaths of the poorest people in the world. The money that we spend on an evening’s entertainment might instead save some poor person from death, blindness, or chronic and severe pain. If we believe that, in our treatment of these poorest people, we are not acting wrongly, we are like those who believed that they were justified in having slaves.

Some of us ask how much of our wealth we rich people ought to give to these poorest people. But that question wrongly assumes that our wealth is ours to give. This wealth is legally ours. But these poorest people have much stronger moral claims to some of this wealth. We ought to transfer to these people [...] at least ten per cent of what we earn. He also concludes that responding to risks to humanity's survival is what "matters most", with humanity's descendants or successors having the potential to spread through the galaxy and create unprecedented good over billions of years.

Personal identity Parfit was singular in his meticulously rigorous and almost mathematical investigations into personal identity. In some cases, he used examples seemingly inspired by Star Trek and other science fiction, such as the teletransporter, to explore our intuitions about our identity. He was a reductionist, believing that since there is no adequate criterion of personal identity, people do not exist apart from their components. Parfit argued that reality can be fully described impersonally: there need not be a determinate answer to the question "Will I continue to exist?" We could know all the facts about a person's continued existence and not be able to say whether the person has survived. He concluded that we are mistaken in assuming that personal identity is what matters in survival; what matters is rather "Relation R": psychological connectedness (namely, of memory and character) and continuity (overlapping chains of strong connectedness).

Following David Hume, Parfit argued that no unique entity, such as a self, unifies a person's experiences and dispositions over time. Therefore personal identity is not "what matters" in survival.

A key Parfitian question is: given the choice between surviving without psychological continuity and connectedness (Relation R) and dying but preserving R through someone else's future existence, which would you choose? Parfit argues the latter is preferable.

Parfit described his loss of belief in a separate self as liberating:

Criticism of personal identity view Mark Johnston rejects Parfit's constitutive notion of identity with what he calls an "Argument from Above". Johnston maintains, "Even if the lower-level facts [that make up identity] do not in themselves matter, the higher-level fact may matter. If it does, the lower-level facts will have derived significance. They will matter, not in themselves, but because they constitute the higher level fact."

In this, Johnston moves to preserve the significance of personhood. Parfit's explanation is that it is not personhood itself that matters, but rather the facts in which personhood consists that provide it with significance. To illustrate this difference between himself and Johnston, Parfit used an illustration of a brain-damaged patient who becomes irreversibly unconscious. The patient is certainly still alive even though that fact is separate from the fact that his heart is still beating and other organs are still functioning. But the fact that the patient is alive is not an independent or separately obtaining fact. The patient's being alive, even though irreversibly unconscious, simply consists in the other facts. Parfit explains that from this so-called "Argument from Below" we can arbitrate the value of the heart and other organs still working without having to assign them derived significance, as Johnston's perspective would dictate.

Population ethics and future generations

Non-identity problem The non-identity problem arises from the observation that actions taken today can fundamentally alter which future people come into existence. In chapter 16 of Reasons and Persons, Parfit posits that one's existence is intimately related to the time and conditions of one's conception. If the moral ramifications of potential policies are considered in person-affecting terms, there is no reason to prefer a sound policy over an unsound one, provided that its effects are not felt by the next few generations.

Parfit eventually became convinced that personal identity is irrelevant to ethics.

Mere addition paradox and repugnant conclusion In part four of Reasons and Persons, Parfit discusses possible futures for the world. Others proposed a minimal threshold of liberties and primary social goods to be distributed, or suggested to adopt a deontological approach that looks to values and their transmission through time. Michael Huemer and Torbjörn Tännsjö endorse the conclusion, considering that the repugnance comes from intuitions that should be revised. In 2021, a number of philosophers said that avoiding the repugnant conclusion was receiving excessive focus and should not be considered a necessary condition for an adequate theory of population ethics.

Against average utilitarianism, Parfit also argues that if all that matters is average happiness, then the best population could be arbitrarily small, for example containing only a few extremely happy individuals. Moreover, this would imply that adding people with lives worth living would make the world worse if these are less happy than the average. They married in 2010.

He supported effective altruism.

Parfit was an avid photographer who regularly traveled to Venice and St. Petersburg to photograph architecture.

Selected works 1964: Eton Microcosm. Edited by Anthony Cheetham and Derek Parfit. London: Sidgwick & Jackson. 1971: "Personal Identity". Philosophical Review. vol. 80: 3–27. 1979: "Is Common-Sense Morality Self-Defeating?". The Journal of Philosophy, vol. 76, pp. 533–545, October. 1984: Reasons and Persons. Oxford: Clarendon Press. 1992: "Against the social discount rate" (with Tyler Cowen), in Peter Laslett & James S. Fishkin (eds.) Justice between age groups and generations, New Haven: Yale University Press, pp. 144–161. 1997: "Reasons and Motivation". The Aristotelian Soc. Supp., vol. 77: 99–130. 2003: 2006: "Normativity", in Russ Shafer-Landau (ed.). Oxford Studies in Metaethics, vol. I. Oxford: Clarendon Press. 2011: On What Matters, vols. 1 and 2. Oxford University Press. ISBN 978-0199572809 and ISBN 978-0199572816 2017: On What Matters, vol. 3. Oxford University Press. ISBN 978-0198778608