A variety of theories have attempted to explain how social movements develop. Some of the better-known approaches are outlined below.

Deprivation Theory

Deprivation theory argues that social movements have their foundations among people who feel deprived of some good(s) or resource(s). According to this approach, individuals who are lacking some good, service, or comfort are more likely to organize a social movement to improve (or defend) their conditions (Morrison 1978).

There are two significant problems with this theory. First, since most people feel deprived at one level or another almost all the time, the theory has a hard time explaining why the groups that form social movements do when other people are also deprived. Second, the reasoning behind this theory is circular – often the only evidence for deprivation is the social movement.

If deprivation is claimed to be the cause but the only evidence for such is the movement, the reasoning is circular (Jenkins and Perrow 1977).

Mass-Society Theory

Mass-Society theory argues that social movements are made up of individuals in large societies who feel insignificant or socially detached. Social movements, according to this theory, provide a sense of empowerment and belonging that the movement members would otherwise not have (Kornhauser 1959). In fact, the key to joining the movement was having a friend or associate who was a member of the movement.

Structural-Strain Theory

Structural-Strain theory proposes six factors that encourage social movement development (Smelser 1962):

1. structural conduciveness - people come to believe their society has problems
2. structural strain - people experience deprivation
3. growth and spread of a solution - a solution to the problems people are experiencing is proposed and spreads
4. precipitating factors - discontent usually requires a catalyst (often a specific event) to turn it into a social movement
5. lack of social control - the entity that is to be changed must be at least somewhat open to the change; if the social movement is quickly and powerfully repressed, it may never materialize
6. mobilization - this is the actual organizing and active component of the movement; people do what needs to be done

This theory is also subject to circular reasoning as it incorporates, at least in part, deprivation theory and relies upon it, and social/structural strain for the underlying motivation of social movement activism. However, social movement activism is, like in the case of deprivation theory, often the only indication that there was strain or deprivation.

Resource-Mobilization Theory

Resource-Mobilization theory emphasizes the importance of resources in social movement development and success. Resources are understood here to include: knowledge, money, media, labor, solidarity, legitimacy, and internal and external support from power elite. The theory argues that social movements develop when individuals with grievances are able to mobilize sufficient resources to take action. The emphasis on resources offers an explanation why some discontented/deprived individuals are able to organize while others are not.

Some of the assumptions of the theory include:

• There will always be grounds for protest in modern, politically pluralistic societies because there is constant discontent (i.e., grievances or deprivation); this de-emphasizes the importance of these factors as it makes them ubiquitous

• Actors are rational; they weigh the costs and benefits from movement participation

• Members are recruited through networks; commitment is maintained by building a collective identity and continuing to nurture interpersonal relationships

• Movement organization is contingent upon the aggregation of resources

• Social movement organizations require resources and continuity of leadership

• Social movement entrepreneurs and protest organizations are the catalysts which transform collective discontent into social movements; social movement organizations form the backbone of social movements