 Contemporary philosophers who have sought to defend versions of moral realism or objectivism have had to come to grips with this basic line of argument, even if they have not always engaged with it explicitly. The Non-cognitivist Argument therefore provides us with a useful tool for mapping out competing positions in metaethics. We can categorize philosophers’ positions negatively in terms of which premises of the noncognitivist argument they accept or  reject.[13]  Some have rejected premise 1, often going on to defend forms of naturalist moral realism that embrace externalism (e.g. Railton 1986; Boyd 1988; Brink 1989). According to the latter views, moral properties are a kind of natural property and moral facts are natural facts. Judgments about these facts express propositions, and so they can be true or false, but these judgment do not necessarily motivate. Whether our moral judgments motivate us is fixed by contingent facts about our psychologies and our substantive moral beliefs. Some have rejected premise 2 (McDowell 1978, 1979), and some of those who have rejected premise 2 have aligned themselves with versions of moral constructivism or rationalism (e.g. Darwall 1983; Scanlon 1998). The latter views take widely varying forms, but they generally see moral principles as requirements of rationality or reason, or as the output of a hypothetical agreement among reasonable, suitably situated persons. Moral reasons are considerations that are motivating, at least when we properly reflect on them, but their motivating force does not depend on a prior desire. Some have rejected both premises 1 and 2, defending forms of nonnaturalist moral realism (Shafer-Landau 2003). Moral properties, on this view, are not identical with natural or descriptive properties, although they may be wholly constituted by them. Moral judgments are intrinsically motivating—they can motivate in the absence of a preexisting desire, but they are not necessarily motivating. Finally, some have accepted both premises 1 and 2, at least appropriately refined, arguing that we can see them both to be compatible with moral cognitivism, and further, with moral realism (Smith 1994). For example, Smith understands the subject matter of judgments about right action as being normative reasons for action. According to him, normative reasons are given by facts about what we would, suitably idealized, want ourselves to desire; and the existence of such facts means that some desires are rationally required. If we believe ourselves to have a normative reason to φ, then rationally we ought to φ, and in judging that we have normative reason to φ, we will necessarily, insofar as we are rational, be moved to φ. The concept of rightness is the concept of what we would, were we fully rational, desire ourselves to desire in our actual world. When we believe it would be right to φ, then, we will, insofar as we are rational, be motivated to φ.