  A wider issue about motivational hedonism is this: is it a contingent claim about an aspect of our psychology that could have been otherwise; or does it posit a law of our psychological nature; or is it a necessary truth about all metaphysically or conceptually or logically possible motivations? The answers to such questions also bear on the sorts of evidence and argument we need if we are fully to appraise motivational hedonism. If it is an empirical psychological thesis, as it seems to be, then it is reasonable to expect application of the methods and evidence of empirical psychology, social inquiry, and perhaps also biological science, to do the main work of appraising it. It is also reasonable to expect that most of this work is to be done by specialist scientists and social scientists through their systematic conduct of meta-analyses of large numbers of empirical studies. Philosophical work will continue to be needed too, to weed out incoherent ideas, to separate out the numerous distinct motivational hedonist theses; and to scrutinize whether, and if so with what significance, various empirical findings actually do bear on these various hedonist theses. For instance, even the feasibility of a research design that is capable of empirically separating out our basic from our non-basic motives would be a serious challenge. Philosophical work can also identify the various features that it is desirable for theories of motivation to have and to be appraised against. Unification, determinacy, and confirmation by cases are treated above as desirable. Other desirable features might include consistency and maximal scope. Philosophers and others can systematically appraise theories of motivation in such terms, including through pairwise comparative assessments of rival theories in terms of those desirable features.