Parfit on act consequentialism

Katarzyna de Lazari-Radek, Peter Singer

Research output: Chapter in Book/Report/Conference proceedingChapter


In the first two volumes of On What Matters, Derek Parfit argues that three major normative theories-Kantianism, Contractualism, and Consequentialism-are, in their most defensible forms, compatible, and can be reconciled as a ‘Triple Theory’. The form of Consequentialism that Parfit argues is compatible with Kantianism and Contractualism is Rule Consequentialism. This has led many to assume that Parfit does not believe that Act Consequentialism is a defensible form of Consequentialism. We draw on personal correspondence to show that this assumption is incorrect. We then consider how, in On What Matters, volume iii, which Parfit completed shortly before his death, he seeks to narrow the differences between Act Consequentialism and the Triple Theory. One of the ways in which he does this is to suggest that Impartial Rationality may be an external rival to Morality, in much the same way as egoism is an external rival to morality. We argue that this move undermines morality, as shown by Parfit’s own example of the judgements that we may make in the case of terror bombing. We conclude that Parfit’s attempts to bridge the gap between Act Consequentialism and Triple Theory meet with only limited success.

Original languageEnglish (US)
Title of host publicationPrinciples and Persons
Subtitle of host publicationThe Legacy of Derek Parfit
PublisherOxford University Press
Number of pages14
ISBN (Electronic)9780192893994
StatePublished - Jan 1 2021

All Science Journal Classification (ASJC) codes

  • General Arts and Humanities


  • Act consequentialism
  • Impartial rationality
  • Morality
  • Rule consequentialism
  • Triple theory


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