The business cycle is the cause of the main fluctuations, indeed of the very nature of strikes themselves; by itself, however, it cannot explain the depth of certain retreats, the amplitude of certain offensives. Political circumstances weigh very heavily and provide the key to the understanding of the major silences and thrusts.

Politics constitutes an important kind of precondition for the eruption of large-scale worker movements, though not being in itself a sufficient one.

The apolitical nature [of trade unions] is a lie, because it cannot exist. Trade unions must have a political outlook … to protect the interests of all workers of any political party or even without a party. To accomplish their goals, trade unions often need the support of political parties. Trade unions have often turned to popular and democratic parties and to their parliamentary groups, in order to lobby for the approval or rejection of a given law, in the workers' best interests.