Talking about the same but different? Understanding social movement and trade union cooperation through social movement and industrial relations theories

In the context of continuing political, social, and economic crises, trade unions in most European countries are seen as weakened, protest as having little influence, and the solidarity between European populations as damaged. Under these circumstances, scientists and practitioners have placed hope in the cooperation of social movements and trade unions in order to revitalise trade unions and achieve common goals. However, the conditions for forming alliances between trade unions and social movement organisations have, thus far, been primarily researched, and partially theorised, from the point of view of different disciplines. In doing so, approaches that emphasise the strategic alignment with resources and context diverge from approaches that highlight the relevance and necessity of shared ideologies or identities. This contribution aims to bring existing approaches from movement and industrial relations research into dialogue with each other and calls for a further integration of both perspectives. It contributes to a more holistic understanding of joint movement and trade union action current concepts such as social movement unionism cannot provide. It uses two examples to show that instrumental, strategy-driven modes and identity-based, culturally-driven modes of cooperation are not contradictory. There are situations in which strategic decisions on resources and political influence are more decisive than ideological proximity and vice versa. These findings are of social and scientific relevance for understanding mechanisms of solidarity construction and processes of bridging differences even in increasingly fragmented and unequal societies.