Many prominent ethicists, including Shelly Kagan, John Rawls, and Thomas Scanlon, accept a kind of epistemic modesty thesis concerning our capacity to carry out the project of ethical theorizing. But it is a thesis that has received surprisingly little explicit and focused attention, despite its widespread acceptance. After explaining why the thesis is true, I argue that it has several implications in metaethics, including, especially, implications that should lead us to rethink our understanding of Reductive Realism. In particular, the thesis (...) of epistemic modesty in ethics implies a kind of epistemic modesty about the metaphysical nature of ethics, if Reductive Realism about the metaphysical nature of ethics is true, and it implies that normative concepts are indispensable to practical deliberation in a way that answers an influential objection to Reductive Realism from Jonathan Dancy, David Enoch, William FitzPatrick, and Derek Parfit. (shrink)