Universality, Modal Realism, and Parfit

Abstract

This article explores relations between moral philosophy and metaphysics in one particular issue: I examine how arguments for universality in morality may contradict with modal realism. This contradistinction is used not because modal realism is a fact or necessarily true but as a part of conceptual analysis of moral terms. And I try to figure out what does this conflict mean for moral philosophy. At first, I present Derek Parfit’s argument for the existence of universality in morality from “Reasons and Persons”. Then I explain why moral philosopher can be interested in modal realism. I present to main motives to it. One motive is based on Kantian ethics. Another is grounded on problems in the interpretation of R.M. Hare’s notion of “supervenience”. Then I prove, using R. Adams’ an argument from indifference, that universality in morality thesis contradicts modal realism. I analyze David Lewis’s response to this argument and some ways to improve Adams’ argument. Finally, I try to dissolve this contradiction by putting some restriction on universality in morality. As a result, it becomes clear what a significant, but rarely emphasized feature is inherent to universality in morality: it should be restricted to one causal closure world.