This paper looks at the phenomenon of ethical vagueness by asking the question, how ought one to reason about what to do when confronted with a case of ethical vagueness? I begin by arguing that we must confront this

question, since ethical vagueness is inescapable. I then outline one attractive answer to the question: we ought to maximize expected moral value when confronted with ethical vagueness. This idea yields determinate results for

what one rationally ought to do in cases of ethical vagueness. But what it recommends is dependent on which substantive theory of vagueness is true; one can’t draw conclusions about how to reason about vagueness in ethics in the absence of concrete assumptions about the nature of vagueness.