The trajectories of American labor-management relations over the industrial era have exerted an enduring fascination dating back to such works as John R. Commons' Trade Unionism and Labor Problems (1905) and Werner Sombart's Why Is There No Socialism in the United States? (1906). In the intervening century, historians from a range of subdisciplines have offered a welter of hypotheses to explain the absence of working-class solidarity, the comparative weakness of American labor unions, and the strength of alliances (paradoxical in a democratic society) that businesses achieved with agencies of the state to counter workers' efforts to achieve political or economic power.