According to Agrippa's trilemma, an attempt to justify something leads to either infinite regress, circularity, or dogmatism. This essay examines whether and to what extent the trilemma applies to ethics. There are various responses to the trilemma, such as foundationalism, coherentism, contextualism, infinitism, and German idealism. Examining those responses, the essay shows that the trilemma applies at least to rational justification of contentful moral beliefs. This means that rationalist ethics based on any contentful moral belief are rationally unjustifiable.

Examining the moral sense theories of Francis Hutcheson, David Hume, and Adam Smith from the perspective of the is-ought problem, this essay shows that the moral sense or moral sentiments in those theories alone cannot identify appropriate morals. According to one interpretation, Hume's or Smith's theory is just a description of human nature. In this case, it does not answer the question of how we ought to live. According to another interpretation, it has some normative implications. In this case, it (...) draws normative claims from human nature. Anyway, the sentiments of anger, resentment, vengeance, superiority, sympathy, and benevolence show that drawing norms from human nature is sometimes morally problematic. The changeability of the moral sense and moral sentiments in Hume's and Smith's theories supports this idea. Hutcheson's theory is morally more appropriate because it bases morality on disinterested benevolence. Yet disinterested benevolence is not enough for morality. There are no sentiments the presence of which alone makes any action moral. (shrink)

This essay shows that a moral sense or moral sentiments alone cannot identify appropriate morals. To this end, the essay analyzes three defenses of Francis Hutcheson's, David Hume's, and Adam Smith's moral sense theories against the relativism charge that a moral sense or moral sentiments vary across people, societies, cultures, or times. The first defense is the claim that there is a universal moral sense or universal moral sentiments. However, even if they exist, a moral sense or moral sentiments alone (...) cannot identify appropriate morals. The second defense is to adopt a general viewpoint theory, which identifies moral principles by taking a general viewpoint. But it needs to employ reason, and even if not, it does not guarantee that we identify appropriate morals. The third defense is to adopt an ideal observer theory, which draws moral principles from sentimental reactions of an ideal observer. Yet it still does not show that a moral sense or moral sentiments alone can identify appropriate morals. (shrink)

David Hume thinks that human affections are naturally partial, while Francis Hutcheson holds that humans originally have disinterested benevolence. Michael Gill argues that Hume's moral theory succeeds over Hutcheson's because the former severs the link between explaining and justifying morality. According to Gill, Hutcheson is wrong to assume that our original nature should be the basis of morality. Gill's understanding of Hutcheson's theory does not fully represent it, since for Hutcheson self-love and self-interest under certain conditions are permissible, or even (...) desirable or necessary for the good of society. There is not much difference between Hutcheson's and Hume's theories in the sense that they both extract impartial morality from human character as it is. Hume's theory does not succeed over Hutcheson's because Hume does not propose a better way of extracting morality nor explain all moral phenomena. (shrink)