In Search of the Trinity: A Dilemma for Parfit’s Conciliatory Project

I outline a dilemma for Derek Parfit’s project to vindicate moral realism. In On What Matters, Parfit argues that the best versions of three of the main moral traditions agree on a set of moral principles, which should make us more confident about the prospects of truth in ethics. I show that the result of this Convergence Argument can be interpreted in two ways. Either there remain three separate and deontically equivalent theories or there remains just one theory, the Triple Theory. Both interpretations fail to deliver what Parfit is looking for. The first interpretation leads to a situation of underdetermination of theory choice that gives rise to a skeptical challenge. The second interpretation jettisons Parfit’s Conciliatory Project, that is, the reconciliation of the three moral traditions. The dilemma, I contend, is the result of Parfit failing to resolve two antithetical lines of thought. His search for the Trinity of moral theorizing must thus fail.