 Value attitudes can be psychologically incompatible, and where they are Locke contends that a hierarchical ranking of values will not resolve the incompatibility. In fact, he suggests that people resolve the incommensurability of their various value attitudes by shifting from one mode of valuation to another. This is why a functional account of values that determines the various value-modes on the basis of underlying psychological states is desirable. Such a theory is better able to achieve a reflective equilibrium with our actual value practices. All values have associated with them a set of imperatives. Locke does not have a great deal to say about how imperatives are formed. Presumably, imperatives are determined, at least in part, by the qualitative character of the value in question. People begin by forming a value-attitude based on one's initial affective response to the object of valuation. As a mediating form of experience a value supplies motivational drives toward acting and refraining from acting in certain ways. Values provide normative direction not only for cognition and psychological drives, but also for action. Imperatives are partially in place as soon as the affective quality of the value is apprehended.