Rationalism, Morality, and Two Dimensions

Abstract

Abstract Basic moral principles are known to us a priori. I will be arguing for this claim, trying to say what it means, and discussing its ramifications. The claim that basic moral principles are a priori was emphasized by Leibniz and, on some natural readings of the texts, endorsed by Kant. Even a selfproclaimed empiricist like Locke sometimes veered towards endorsing this claim of a priori status. Yet the character of this a priori status, and its significance for the epistemology and metaphysics of moral claims, have both been very largely lost in recent discussions of moral thought. I will be arguing that the nature of this a priori status is incompatible with subjectivist, judgement-dependent and mind-dependent treatments of moral thought. Part of the task in establishing this incompatibility is to articulate more precisely the kind of a priori status that is in question here. It is easy to underestimate the problem for mind-dependent theories of moral thought if one starts by understating the sense in which basic moral principles are a priori.