What is involved in taking a realist approach to social science knowledge? Most generally, realism involves the view that at least some of the assertions of a field of knowledge make true statements about the properties of unobservable things, processes, and states in the domain of study. Several important philosophers of science have taken up this issue in the past three decades, including Rom Harre (Causal Powers: Theory of Natural Necessity) and Roy Bhaskar (A Realist Theory of Science). Peter Manicas's recent book, A Realist Philosophy of Social Science: Explanation and Understanding, is a useful step forward within this tradition. Here is how he formulates the perspective of scientific realism:
The real goal of science ... is understanding of the processes of nature. Once these are understood, all sorts of phenomena can be made intelligible, comprehensible, unsurprising. (14)
Explanation ... requires that there is a "real connection," a generative nexus that produced or brought about the event (or pattern) to be explained. (20)So realism has to do with discovering underlying processes that give rise to observable phenomena. And causal mechanisms are precisely the sorts of underlying processes that are at issue. Here is how Manicas summarizes his position:
Theory provides representations of the generative mechanisms,including hypotheses regarding ontology, for example, that there are atoms, and hypotheses regarding causal processes, for example, that atoms form molecules in accordance with principles of binding. We noted also that a regression to more fundamental elements and processes also became possible. So quantum theory offers generative mechanisms of processes in molecular chemistry. Typically, for any process, there will be at least one mechanism operating, although for such complex processes as organic growth there will be many mechanisms at work. Theories that represent generative mechanisms give us understanding. We make exactly this move as regards understanding in the social sciences, except that, of course, the mechanisms are social. (75)Manicas's illustrations of causal powers and mechanisms are most often drawn from the natural world. But what basis do we have for thinking that social entities have stable causal properties -- let alone a profile of causal powers that are roughly invariant across instances?
Consider an example, Theda Skocpol's definition of social revolutions:
Social revolutions are rapid, basic transformations of socio-economic and political institutions, and--as Lenin so vividly reminds us--social revolutions are accompanied and in part effectuated through class upheavals from below. It is this combination of thorough-going structural transformation and massive class upheavals that sets social revolutions apart from coups, rebellions, and even political revolutions and national independence movements. (link)Realism invites us to consider whether "social revolutions" really have the characteristics she attributes to them. Do social revolutions have an underlying nature distinctive causal powers that might be identified by a social theory? More generally, what basis do we have for thinking that certain types of social entities possess a specific set of causal powers?
The answer seems to be, very little. Types of social entities -- revolutions, states, riots, market economies, fascist movements -- are heterogeneous groupings of concrete social formations rather than "kinds" along the lines of "metal" or "gene". Each of the extended historical events that Skocpol offers as instances of the category "social revolution" is unique and contingent in a variety of ways; these historical episodes do not share a common causal nature. It is legitimate to group them together under the term "social revolution"; but it is essential that we not commit the error of reification and imagine that the group so constituted must share a fundamental causal nature in common. So the most direct application of this kind of realism to the social sciences seems somewhat unpromising.
But we are on firmer ground when we consider a particularly central type of assertion in the social sciences: claims about underlying causal mechanisms or social processes. So what does it mean to assert that a given social mechanism "really exists"?
Take the idea of "stereotype threat" as one of the mechanisms underlying an important social fact, the racial and gender differences in performance that have been observed on some standardized tests (Claude Steele and Joshua Aronson, "Stereotype Threat and the Intellectual Test Performance of African Americans" (link); see also this article in the Atlantic). We can summarize the theory along these lines: "Prevalent assumptions about the characteristics and performance of various salient social groups can depress (or enhance) the performance of members of those groups on intellectual and physical tasks. This provides a partial explanation of the observed differentials in performance." This mechanism is hypothesized as one of the ways in which performance by individuals in various groups is socially influenced in such a way as to lead to differential performance across groups. It postulates a set of internal psychological mechanisms surrounding cognition and problem-solving, all related to the individual's self-ascribed social identity.
The realism question is this: do these hypothetical psychological effects actually occur in real human individuals? And do these differences in cognitive processes lead to differential performance across groups? If we confirm both these points, then we can conclude that "stereotype threat is a real social psychological mechanism." The microfoundations of this mechanism reside in two locations: the concrete cognitive processes of the individuals, and the social behaviors of persons around these individuals, giving subtle cues about stereotypes that are discerned by the test-taker.
So we might say that we can conclude that a postulated social mechanism "really" exists if we are able to provide piecemeal empirical and theoretical arguments demonstrating that the terms of the mechanism hypothesis are confirmed in the actions and behavior of agents; and that these patterns of action do in fact typically lead to the sorts of outcomes postulated. In other words, we need to look at our hypotheses about social mechanisms as small, somewhat separable theories that need separate empirical, historical, and theoretical evaluation. And when we are successful in providing convincing support for these mechanism-theories, we are also justified in concluding that the postulated mechanism really exists. The social world really embodies stereotype threat if individuals are really affected in their cognitive performances by the sorts of subtle behavioral cues mentioned by the theory, in roughly the ways stipulated by the theory. And we will feel most confident in this assertion if we also find new areas of behavior where this mechanism also appears to be at work.
This approach has an important implication about social ontology. The reality of a social mechanism is dependent on facts about agents, their characteristics of agency, and the environment of social relationships within which they act. So there is a close intellectual relationship between the ontology of methodological localism and realism about causal mechanisms.
(The smokestack image above illustrates a different kind of social mechanism -- the workings of externalities in a market economy, creating pollution by dumping public harms to save private costs.)