Economics is the study of the whole system of exchange relationships. Politics is the study of the whole system of coercive or potentially coercive r… - James M. Buchanan

Individuals do not act so as to maximize utilities described in independently-existing functions. They confront genuine choices, and the sequence of decisions taken may be conceptualized, ex post (after the choices), in terms of “as if” functions that are maximized. But these “as if” functions are, themselves, generated in the choosing process, not separately from such process. If viewed in this perspective, there is no means by which even the most idealized omniscient designer could duplicate the results of voluntary interchange. The potential participants do not know until they enter the process what their own choices will be. From this it follows that it is logically impossible for an omniscient designer to know, unless, of course, we are to preclude individual freedom of will.

A version of the old fable about the king's nakedness may be helpful here. Public choice is like the small boy who said that the king really has no clothes. Once he said this, everyone recognized that the king's nakedness had been recognized, but that no-one had really called attention to this fact.

The hard core in public choice can be summarized in three presuppositions: (1) methodological individualism, (2) rational choice, and (3) politics-as-exchange.