This book explores the idea that there is a gray area in ethics. My central claim is that some acts are somewhat right and somewhat wrong, meaning that deontic concepts such as RIGHT and WRONG (capitalized to indicate that we are discussing the concepts and not the entities they refer to) are gradable. Philosophical theories of indeterminacy and vagueness can shed light on some aspects of the gradualist hypothesis, but they leave important questions open. It is, for instance, not clear what a morally conscientious agent should do if she must choose among options that are somewhat right and somewhat wrong.

Moral indeterminacy is not the same thing as moral vagueness. In this chapter, I reserve the term “indeterminacy” for phenomena that are indeterminate but not vague. The term “vagueness” is reserved for entities that are susceptible to a sorites series. The distinction between moral indeterminacy and vagueness mirrors an analogous distinction between two versions of the gradualist hypothesis. According to the first, some acts are somewhat right and somewhat wrong in the indeterministic sense; according to the second, some acts are somewhat right and somewhat wrong because they display moral vagueness. These hypotheses must be kept apart because they sometimes entail different practical verdicts. The first aim of this chapter is to clarify the notions of moral indeterminacy and vagueness that are central to these two versions of the gradualist hypothesis. The second aim is to discuss reasons for believing that morality is vague, or indeterminate but not vague, or both, and whether we should understand all these views as ontic, semantic, or epistemic theories.