A few years ago, Goodwin and Jasper (2004) depicted the political process approach to social movements as the dominant paradigm in the study of social movements and contentious politics. The concept of political opportunities lies at the core of this approach. Political opportunities can be defined broadly as "consistent but not necessarily formal, permanent, or national signals to social or political actors which either encourage or discourage them to use their internal resources to form social movements" (Tarrow 1996: 54, emphasis in original). More specifically, they refer to those aspects of the political system that affect the possibilities that challenging groups have to mobilize effectively. In this sense, opportunities are "options for collective action, with chances and risks attached to them, which depend on factors outside the mobilizing group" (Koopmans 2004: 65). Four main dimensions of political opportunity have been stressed in the literature (McAdam 1996): (1) the relative openness or closure of the institutionalized political system; (2) the stability or instability of that broad set of elite alignments that typically undergird a polity; (3) the presence or absence of elite allies; and (4) the state's capacity and propensity for repression.
Chuck Tilly undoubtedly was the most prominent among those scholars who have made the concept of political opportunities so central to the field during the past thirty to forty years. In this brief essay I would like to discuss the use of this concept in the social movement literature as well as stress Tilly's fundamental contribution in its origin and conceptualization. After having recalled Tilly's legacy on this concept, I will deal with the criticisms it has received. Finally, I will mention some recent developments that have tried to avoid some of the pitfalls in the use of this concept.
We can hardly overestimate Tilly's contribution to the study of social movements and contentious politics. Among his numerous contributions is his impulse for what has become known as the political process approach