According to Steven Lukes ‘A exercises power over B when A affects A in a manner contrary to B's interests’. Although he is not willing to contend that this general concept of power is altogether beyond reasonable dispute Lukes argues that it is the specific conceptions of power to which this more general concept gives rise when we fill in what is to count as B's interests that pose the fundamental problem for social and political science. For, although the conceptions are, to some degree, assessable in terms of their descriptive accuracy and explanatory scope, they are also ‘ineradicably evaluative’ and ‘essentially contested’. Three important ‘normatively specific conceptions of interests’, implying three corresponding conceptions of power, particularly concern him:
(1) the liberal conception, which relates men's interests to what they actually want or prefer, to their policy preferences as manifested by their political participation; (2) the reformist conception, which, deploring that not all men's wants are given equal weight within the political system, also relates their interests to what they actually want and prefer, but allows that this may be revealed in the form of deflected, submerged, or concealed wants and preferences; and (3) the radical conception, which maintains that men's wants may themselves be a product of a system which works against their interests and, in such cases, relates the latter to what men would want and prefer, were they able to make the choice.