  Although terms such as ‘fitting’, ‘appropriate’, and the like are often used interchangeably, there are several distinct forms of endorsement one can give to evaluative attitudes (such as emotions and desires), and the failure to differentiate adequately between them gives rise to the central outstanding problem facing FA theory: the wrong kind of reason problem. Consider the simplest form of FA theory, which analyzes goodness in terms of what it is fitting to desire: the desirable. Not all considerations in favor of desiring something manifest its desirability; for instance, incentives and sanctions attached to desire do not. Perhaps desiring certain good things (such as happiness) makes one less likely to succeed in getting them. If so, then that seems a good reason not to desire happiness, but it clearly does not show that happiness isn't desirable. Thus FA theories must explicate a notion of fittingness that can distinguish reasons of the right kind: those relevant to evaluative judgment of the object. Moreover, the evaluative attitudes used by the theory must not already involve the value concept it attempts to explicate, on pain of circularity. If to desire something involves thinking it good, for example, then an FA theory of goodness in terms of fitting desire seems circular. However, certain FA accounts claim, at least with respect to more fine-grained attitudes and specific values, that such circularity is not vicious because it does real explanatory work.