- According to social scientists Lipset and Rokkan, for a social grouping to be termed a social cleavage, it must meet three conditions. First, there must be a division in society based on a particular demographic or socioeconomic factor. Examples of such factors are class, vocation, ethnic group and religious affiliation. This characteristic must serve to separate them from other members of society. Second, people on one side of a social divide (or cleavage) must be aware of the characteristic that bonds them together, and they must demonstrate willingness to act to promote the interests associated with their social identity. Finally, there must be some sort of institution in place that can provide organizational support to the interests of those on a particular side of the social divide.
- Seymour Martin Lipset and Stein Rokkan developed the theory of social cleavages in the 1960s as they examined political behavior displayed in Western Europe. They asserted that the political trends being observed were the result of decades-old social divides framed in terms of class, religion and region. Therefore they began to see divides over the breadth of the state's influence and the moral character that defined "family" as not just individual issues but patterns of political behavior that stemmed from these deep-seated social divides.
- Social cleavages can be used to describe how political party systems are formed within a society. As groups exhibit disparate voting tendencies based on fractures in society, they associate more and more with bodies of ideological thought that turn into political parties. The breakdown of party affiliation and proportion of representation in each party solidifies over time, as people exhibit the same voting behavior based on the same social rifts. With the passage of time, then, party systems emerge, with old parties carrying the same constituencies decade after decade and defining the political landscape of the society.
- The party systems described by Lipset and Rokkan were built on such strong fundamental divides that they were able to consistently withstand attempts by other parties to enter the political fray. The 1970s, though, saw an explosion of minor party participation that seemed to defy the traditional groupings. Many suggested, therefore, that the Lipset and Rokkan analysis no longer applied because society had been mobilized to action based upon a diversity of modern motivations, which dismissed the uniform block voting of the past.
- Others have endorsed the continued use of the term social cleavages but adapted it for a less rigid purpose than that which Lipset and Rokkan had in mind. In this viewpoint, the party system itself, as seen in sheer number of distinct parties, is not the most important factor to determine inherent social divides. Instead, the diversity of hidden social conflicts is where social cleavages lie. Party loyalties, then, take a back seat to specific issues in society, which party elites try to harness to sway voters.
