 “Anti-realism,” “non-realism,” and “irrealism” may for most purposes be treated as synonymous. Occasionally, distinctions have been suggested for local pedagogic reasons (see, e.g., Wright 1988; Dreier 2004), but no such distinction has generally taken hold. (“Quasi-realism” denotes something very different, to be described below.) All three terms are to be defined in opposition to realism, but since there is no consensus on how “realism” is to be understood, “anti-realism” fares no better. Crispin Wright (1992: 1) comments that “if there ever was a consensus of understanding about ‘realism’, as a philosophical term of art, it has undoubtedly been fragmented by the pressures exerted by the various debates—so much so that a philosopher who asserts that she is a realist about theoretical science, for example, or ethics, has probably, for most philosophical audiences, accomplished little more than to clear her throat.” This entry doesn’t purport to do justice to the intricacy and subtlety of the topic of realism; it should be acknowledged at the outset that the fragmentation of which Wright speaks renders it unlikely that the label “moral anti-realism” even succeeds in picking out a definite position. Yet perhaps we can at least make an advance on clearing our throats.