Oughts, Thoughts, and Companions in Guilt: A Defense of Moral Realism

According to the moral error theory, there are no moral facts: all (positive, atomic) moral judgements are systematically and uniformly false. A popular strategy in recent years for arguing against the moral error theory is to deploy a companions in guilt (CG) argument. According to CG theorists, arguments for the moral error theory are insufficient, because either they rely on premises which do not warrant scepticism about moral facts, or they threaten to support an implausible error theoretic conclusion in other areas of discourse – areas which seem safe from such a conclusion. This thesis deploys a CG argument in order to defend moral realism – roughly, the view that moral judgements purport to state facts and that some of those judgements have true contents – against one influential argument for the error theory: J. L. Mackie’s argument from queerness. The CG argument deployed depends on the assumption that doxastic normativism is true. Doxastic normativism is a metaphysical thesis according to which norms are in some sense constitutive of, or essential to, belief. Since my CG argument only works (if it works) on the assumption that doxastic normativism is true, much of this thesis is spent defending normativism against some of its influential detractors