Kantian Cognitivism

According to many of its advocates, one of the main attractions of Kantian moral philosophy is its metaethical innocence. The most interesting argument for such innocence appeals to Kantians' rationalism. Roughly, if moral action is simply rational action, then we do not need to appeal to anything beyond rationality to certify moral judgment. I assess this argument by reflecting on (dis)analogies between moral and logical forms of rationalism. I conclude that the Kantian claim to metaethical innocence is overstated. Kantians cannot avoid substantial metaethical commitments. Or if they can, it is not their rationalism that explains why this is so.