Abstract

The word 'rationalism,' as it appears in philosophical discussions of ethics and morality, signifies at least one of a cluster of theses, each of which connects some aspect of ethical experience to reason or rationality. The most provocative rationalist thesis arises in contemporary discussions in metaethics; and it is this thesis that remains the most likely referent, in contemporary discussions, of the phrase 'moral rationalism.' The thesis is more accurately referred to, however, as metaethical rationalism, since it concerns the provenance and nature of moral obligations, rather than their substance. A strong version of metaethical rationalism maintains that if someone is morally obligated to perform a certain action, then performing that action is what she has the strongest reasons, all things considered, to do. A weaker version of metaethical rationalism claims that if someone is morally obligated to perform a certain action, then performing that action is something that she has a reason to do, even though the reason might not be decisive: another reason, for instance of prudence, might trump the reason she has to act morally. It is rationalism in this metaethical guise that will be the ultimate focus of this essay.