Elite theory focuses our attention on the role of leadership in policy formation and on the reality that in any political system, a few govern the many. Whether elites rule and determine policy, with little influence from the masses, is a difficult proposition to handle. It cannot be proved merely by assertions that the "establishment runs things," which has been a familiar plaint in recent years. Political scientist Robert Dahl argues that to defend the proposition successfully, one must identify "a controlling group, less than a majority in size, that is not a pure artifact of democratic rules... a minority of individuals whose preferences regularly prevail in cases of differences of preferences on key political issues." It may be that elite theory has more utility for analysis and explanation of policy formation in some political systems, such as developing or Eastern European countries, than in others, such as the pluralist democracies of the United States and Canada. Sociologist William Domhoff has long argued, however, that there is an American upper class, based on the ownership and control of large corporations, which is in fact a governing class.