Structural Cohesion and Embeddedness: A Hierarchical Concept of Social Groups

Although questions about social cohesion lie at the core of our discipline, definitions are often vague and difficult to operationalize. Here research on social cohesion and social embeddedness is linked by developing a concept of structural cohesion based on network node connectivity. Structural cohesion is defined as the minimum number of actors who, if removed from a group, would disconnect the group. A structural dimension of embeddedness can then be defined through the hierarchical nesting of these cohesive structures. The empirical applicability of nestedness is demonstrated in two dramatically different substantive settings, and additional theoretical implications with reference to a wide array of substantive fields are discussed. “[S]ocial solidarity is a wholly moral phenomenon which by itself is not amenable to exact observation and especially not to measurement.” (Durkheim [1893] 1984:24) “The social structure [of the dyad] rests immediately on the one and on the other of the two, and the secession of either would destroy the whole. . . . As soon, however, as there is a sociation of three, a group continues to exist even in case one of the members drops out.” (Simmel [1908] 1950:123) Questions surrounding social solidarity are foundational for sociologists and have engaged researchers continuously since Durkheim. Researchers across a wide spectrum of substantive fields employ "cohesion" or "solidarity" as a key element of their work. Social disorganization theorists, for example, tout the importance of “community cohesion” for preventing crime (Sampson and Groves 1989). Political sociologists focus on how a cohesive civil society promotes democracy (Paxton 1999; Putnam 2000). Historical sociologists point to the importance of solidarity for revolutionary action (Bearman 1993; Gould 1991), and that the success of heterodox social movements depends on a cohesive critical mass of true believers (Oliver, Marwell, and Teixeira 1985). Social epidemiologists argue that a cohesive “core” is responsible for the persistence of sexually transmitted diseases (Rothenberg, Potterat, and Woodhouse 1996). Worker solidarity is a key concept in the sociology of work (Hodson 2001). Social psychologists have repeatedly returned to issues surrounding cohesion and solidarity, attempting to understand both its nature (Bollen and Hoyle 1990; Gross and Martin 1952; Roark and Shara 1989; Roark and Shara 1989) and consequences (Carron 1982; Hansell 1984). Unfortunately, as with “structure” (Sewell 1992), the rhetorical power of “cohesion” is both a blessing and a curse. Sociologists are all too familiar with the problem: We study “cohesion” in almost all our substantive domains, and in its ambiguity, it seems to serve as a useful theoretical placeholder. Ubiquity, however, does not equal theoretical consistency. Instead, the exact meaning of cohesion is often left vague, or when specified, done in a particularistic manner Structural Cohesion and Embeddedness that makes it difficult to connect insights from one subfield to another. We identify one generalizable structural dimension of social solidarity. Although the concept we develop is related in certain ways to some, perhaps many, of the meanings of “solidarity” or “cohesion” used in the literature, it is by no means intended to incorporate them all. Instead, we focus on only one dimension. By carefully identifying one aspect of social solidarity, we hope to help clarify one of the multiple meanings contained in this ubiquitous idea. The social network based concept we develop is theoretically grounded in insights from Simmel ([1908] 1950) and Durkheim ([1893] 1984) and methodologically grounded in classical graph theory (Harary, Norman, and Cartwright 1965; Harary, 1969). D. White and Harary (2001) demonstrate the formal logic by which graph-theoretic measures lend themselves to the study of the structural dimension of social cohesion. Here, we extend a definition of structural cohesion in its most general form, applicable to large-scale analyses in a variety of settings, and provide an algorithm for its use in empirical analyses. The implementation of our algorithm for measuring embedded levels provides an operational specification of one dimension of social embeddedness (Granovetter 1985, 1992), which allows us to specify and explore empirically the unique contribution of this dimension. Here we focus on two empirical settings: friendships among highschool students (Bearman, Jones, and Udry 1996) and the political activity of big businesses (Mizruchi, 1992). For adolescent friendships, we show that network position predicts school attachment, using structural cohesion to link the relational to the ideational components of solidarity in a dozen large networks. For the smaller director-interlock network, we show that joint network embeddedness leads dyads to make similar political contributions; linking network position to coordinated political action. In both cases, we find independent effects for our conception of cohesion net of commonly used alternative measures, substantiating its unique contribution.