Social movement theory is an interdisciplinary study within the social sciences that generally seeks to explain why social mobilization occurs, the forms under which it manifests, as well as potential social, cultural, political, and economic consequences, such as the creation and functioning of social movements.

Classical approaches The classical approaches emerged at the turn of the century. These approaches have in common that they rely on the same causal mechanism. The sources of social movements are structural strains. These are structural weaknesses in society that put individuals under a certain subjective psychological pressure, such as unemployment, rapid industrialization or urbanization. When the psychological disturbance reaches a certain threshold, this tension will produce a disposition to participate in unconventional means of political participation, such as protesting. Additionally, these approaches have in common that they view participation in contentious politics as unconventional and irrational, because the protests are the result of an emotional and frustrated reaction to grievances rather than a rational attempt to improve their situation.Stekelenburg, J. van en Klandermans, B. (2009). "Social movement theory: Past, present and prospect", Movers and Shakers, 17-43. These psychologically-based theories have largely been rejected by present-day sociologists and political scientists, although many still make a case for the importance (although not centrality) of emotions. See the work of Gustav LeBon, Herbert Blumer, William Kornhauser,Kornhauser, William. The Politics of Mass Society. Glencoe, Ill.: The Free Press, 1959. and Neil Smelser.Smelser, Neil J. 1962 Theory of Collective Behavior. London: Collier-Macmillan.

Deindividuation model

Sociologists during the early and middle-1900s thought that movements were random occurrences of individuals who were trying to emotionally react to situations outside their control.

Leon Festinger was an American social psychologist who coined the term deindividuation. Festinger and colleagues suggested that experiencing deindividuation, especially within a group setting, diminishes typical inhibitions on behavior, leading individuals to engage in actions they might otherwise refrain from, as they feel less directly responsible for their conduct.

An important writer in this area of research was Gustave LeBon. In his book The Crowd, he studied the collective behavior of crowds. What he concluded was that once an individual submerges in a crowd, his behavior becomes primitive and irrational and he is therefore capable of spontaneous violence.LeBon, G. (1897). The Crowd. London: Unwin. This transformation happens under certain conditions. Once individuals submerge themselves in a crowd, they gain a sense of anonymity and this causes them to believe that they cannot be held accountable for their behavior within the crowd. This is combined with a sense of invisibility by being part of a crowd. Under these conditions, critical reasoning is impossible and an unconscious personality emerges: a personality which is dominated by destructive instincts and primitive beliefs. This theory has been picked up and further developed by other theorists like Herbert Blumer and Neil Smelser.

Mass society theory Mass society theory emerged in the wake of the fascist and communist movements in the 1930s and 1940s and can be seen as an attempt to explain the rise of extremism abroad. One prime example of extremism abroad is the rise of fascism in Europe during the twentieth century. Characterized by totalitarian rule, nationalist fervor, and racial discrimination, fascist regimes such as those led by Mussolini in Italy and Hitler in Germany imposed authoritarian control and propagated aggressive expansionism.

The central claim of mass society theory is that socially isolated people are more vulnerable to extremism.

An important underpinning of this theory is Émile Durkheim's analysis of modern society and the rise of individualism. Durkheim stated that the emergence of the industrial society caused two problems:

Anomie: There were insufficient ways to regulate behavior due to the increasing size and complexity of the modern society. Egoism: The excessive individuation of people due to the weakening of local communities.

These problems signify a weakened restraining social network to control the behavior of individuals. According to Durkheim, this will lead to dysfunctional behavior, such as suicide.Durkheim, E. (1897) Suicide. Free Press, New York.

Arthur Kornhauser applied this theory to social movements in his book The Politics of Mass Society. He stated that in a mass society, anomie and egoism cause small local groups and networks to decline. What is left after this are powerful elites, massive bureaucracies, and isolated individuals. In this society, intermediate buffers between the elite and the non-elite erode and normal channels for non-elites to influence elites become ineffective. This makes non-elites feel more alienated, and therefore more susceptible to extremism.Kornhauser, W. (1959) Politics of Mass Society. London: Routledge.

Relative deprivation

People are driven into movements out of a sense of deprivation or inequality, particularly (1) in relation to others or (2) in relation to their expectations. In the first view, participants see others who have more power, economic resources, or status, and thus try to acquire these same things for themselves. In the second view, people are most likely to rebel when a consistently improving situation (especially an improving economy) stops and makes a turn for the worse. At this point, people will join movements because their expectations will have outgrown their actual material situation (also called the "J-Curve theory"). See the work of James Davies, Ted Gurr,Gurr, Ted. Why Men Rebel. Princeton: Princeton University Press, 1970. and Denton Morrison.

Contemporary approaches During the 1960s there was a growth in the amount of social movement activity in both Europe and the United States. With this increase also came a change in the public perception around social movements. Protests were now seen as making politics better and essential for a healthy democracy. The classical approaches were not able to explain this increase in social movements. Because the core principle of these approaches was that protests were held by people who were suffering from structural weaknesses in society, it could not explain that the growth in social movement was preceded by a growth in welfare rather than a decline in welfare. Therefore, there was a need for new theoretical approaches.

Because deprivation was not a viable explanation anymore, researchers needed to search for another explanation. The explanations that were developed were different in the United States than in Europe. The more American-centered structural approaches examined how characteristics of the social and political context enable or hinder protests. The more European-centered social-constructivist approaches rejected the notion that class-struggle is central to social movements, and emphasized other indicators of a collective identity, like gender, ethnicity or sexuality.

Structural approaches

Political opportunity/political process

Certain political contexts should be conducive for potential social movement activity. There are two important approaches structuralist and constructivist. The main difference between the structuralist and constructivist approaches through communication is that constructivism focuses on more communication. Structuralism is more centered around the consequences of human interaction. These climates may [dis]favor specific social movements or general social movement activity; the climate may be signaled to potential activists and/or structurally allowing for the possibility of social movement activity (matters of legality); and the political opportunities may be realized through political concessions, social movement participation, or social movement organizational founding. Opportunities may include:

Increased access to political decision making power Instability in the alignment of ruling elites (or conflict between elites) Access to elite allies (who can then help a movement in its struggle) Declining capacity and propensity of the state to repress dissent

Resource mobilization

Social movements need organizations first and foremost. Organizations can acquire and then deploy resources to achieve their well-defined goals. To predict the likelihood that the preferences of a certain group in society will turn into protest, these theorists look at the pre-existing organization of this group. When the population related to a social movement is already highly organized, they are more likely to create organized forms of protest because a higher organization makes it easier to mobilize the necessary resources. A states policing strategy (repression or reform) can constrain or expand an organizations ability to deploy or use their resources. For example, harsh policing could strengthen moral resources and in turn strengthen cultural resources, bolstering a social movement. Some versions of this theory state that movements operate similar to capitalist enterprises that make efficient use of available resources. Scholars have suggested a typology of five types of resources:

Material (money and physical capital); Morale (solidarity, support for the movement's goals); Social-Organizational (organizational strategies, social networks, bloc recruitment); Human (volunteers, staff, leaders); Cultural (prior activist experience, understanding of the issues, collective action know-how) Political Process Theory

Political Process Theory explores how movements arise and succeed through analyzing political opportunity structures, resource access, and collective identity formation. This theory emphasizes the interaction between marginalized groups and their political environment, by focusing on openings in power structures that allow for the advancement of movements. McFarland discusses how power dynamics and institutional responsiveness determine if grievances evolve into organized action. This theory underscores the importance of framing, alliances and political vulnerabilities, arguing that movements often thrive when exploiting a shift in power or norms.

Social movement impact theory

This body of work focuses on assessing the impact that a social movement has on society, and what factors might have led to those impacts. The effects of a social movement can resonate on individuals,McAdam, Doug. The biographical impact of activism. Minneapolis, MN: University of Minnesota Press, 1999. institutions,Moore, Kelly. "Political protest and institutional change: The anti-Vietnam War movement and American science." How social movements matter 10: 97. 1999 cultures,Ferree, Myra Marx and Beth B. Hess. Controversy & Coalition: The New Feminist Movement across Three Decades of Change, New York: Twayne Publishers. 1994. or political systems. While political impacts have been studied the most, effects on other levels can be at least as important. Because Impact Theory has many methodological issues, it is the least studied of the major branches of Social Movement Theory.Giugni, Marco, Doug McAdam, and Charles Tilly. How Social Movements Matter. Minneapolis, MN. The Regents of the University of Minnesota, 1999. Nevertheless, it has sparked debates on the efficacy of violence,Gamson, William. Strategy of Social Protest. Belmont: Wadsworth Publishing Company. 1975. the importance of elite and political allies, and the agency of popular movements in general.

Social-constructivist approaches

New social movements