The distinction between resource mobilization and political process theories evolved at the end of the 1970s. The Emile Durkheimian tradition emphasizes disintegration and anomie and sharply distinguishes between routine and nonroutine forms of collective action. The mobilization model analyzes the actual process of conflict from the perspective of a single contender. McAdam begins with a critique of the "classical model" of social movements exemplified by collective behavior theory. Collective behavior was thereby seen as a psychological expression of discontent triggered by strain rather than a rational response to political grievances deriving from group interests. Sidney Tarrow defines movements as 'collective challenges by people with common purposes and solidarity in sustained interaction with elites, opponents, and authorities'. Resource mobilization advocates made the polemical claim that grievances were all but irrelevant for explaining collective action, and that they sometimes emerged in response to resource availability rather than the other way around.