What is most interesting in paying attention to social life is noticing the surprising outcomes that often materialize from a number of uncoordinated choices and actions by independent individuals. We want to understand why and how the aggregate-level social fact came to be: was it a set of features of the individual actors' preferences or decision-making? Was it the unintended result of strategic choices by various actors? Was it simply the path-dependent and contingent outcome of a serial interactive process? Was it brought about by structural conditions -- power, wealth, race -- within the context of which actors made their choices? And what were the mechanisms of constraint, aggregation, contagion, and escalation through which actions and processes at the more proximate level came together into the outcome at the distal level?
Consider a pair of examples. Kitty Genovese is attacked by an assailant over an extended period of time in a dense neighborhood in Queens, many people observe the crime, and no one intervenes. The woman is eventually murdered. The question here is, why was there a total absence of intervention by any individual or group in this crime? And a parallel surprise: General Marcus Licinius Crassus, having trapped the rebellious slave army of Spartacus, announces that the slaves will be spared death if they give up Spartacus for crucifiction. Spartacus rises to his feet to say, "I am Spartacus." And in minutes the army of men rise as well, all declaring "I am Spartacus." Here the question is the reverse: why do these men expose themselves to death to stand in solidarity with Spartacus? In each case, there is an occasion for action presented to a group of individuals, in which members of the group can attempt to save the life of another person. The collective behavior is fundamentally different in the two cases. Why so? What are the mechanisms, psychological and social, that led to non-intervention in the first case and fatal solidarity in the second?
We might form a number of hypotheses about both of these cases in order to explain the very different outcomes. In the Kitty Genovese case, we might cite anomy and anonymity as possible causes of the lack of response by bystanders. With a low level of civic bonds, perhaps city dwellers have such a low level of emotional involvement with each other that even the slightest effort is unjustified. Or perhaps it is the fact that each potential responder is anonymous to the others that leads to the result; he/she can make the decision to refrain from offering aid without fear of criticism from others. Or perhaps collective behavior is strongly influenced by the actions of the first few, with later observers mimicking earlier non-aiders. So the outcome might have been highly different if the first or second witness had intervened; others might have followed suit. In the case of Spartacus, we might hypothesize that the bonds of solidarity forged by a history of fighting the Roman army gave the soldiers the moral motivation to support Spartacus; or perhaps it is the publicity of the scene, or the early example of the first few supporters, that spread to the behavior of the others. Or perhaps it is an expression of fundamental mistrust by the soldiers of the good faith of Marcus Crassus; "he will kill us anyway." With nothing to lose, the army makes its symbolic statement of rejection. These are each social psychological hypotheses, concerning the ways that individuals choose to involve themselves in an emergency and a situation of potential sacrifice.
Each of these hypotheses represents a social mechanism that can be incorporated into a narrative explaining the aggregate outcome. In order for such a story to be scientifically compelling, we need to have some way of using empirical evidence to evaluate whether the postulated mechanism actually works in the real world of human behavior. Is there empirical evidence for a social psychology of mimicry? Do we have evidence to suggest that members of a crowd are more likely to do X or Y if a few others have already done so? Is there empirical support for a theory of solidarity as a social motivation: do combat teams, groups of deep-ground miners, or emergency room doctors develop a higher willingness to conform their behavior to the good of the group or of other individuals in the group? These examples of social mechanisms all fall in the category of putative behavioral regularities, and it should be possible to investigate them experimentally and statistically.
The challenge of explanation for any social outcome, we might say, is that of constructing an interpretation of the states of minds of a set of actors; the constraints and opportunities within which they choose a course of action; and the interactions that are created as they act within a common environment, leading to the outcome in question. This is what we can refer to as an aggregative explanation, and it lies at the heart of Thomas Schelling's methodology in Micromotives and Macrobehavior. As Schelling points out, sometimes the explanation turns on specific features of agency (the actors' preferences or their modes of decision-making), and sometimes it turns on the specifics of the environment of choice (the fact that the outcome of action is a public good). But in general, explanation proceeds by showing how agents with specific features, acting within a social and natural environment with specific characteristics, bring about specific kinds of outcomes.
This, in a nutshell, represents a simple but powerful statement of a philosophy of social explanation. It also represents the rudiments of a social ontology: higher-level social features are composed of the actions and states of agency of a set of actors within the context of locally embodied rules, norms, and expectations. This is what I refer to as "methodological localism":
This theory of social entities affirms that there are large social structures and facts that influence social outcomes. But it insists that these structures are only possible insofar as they are embodied in the actions and states of socially constructed individuals. The “molecule” of all social life is the socially constructed and socially situated individual, who lives, acts, and develops within a set of local social relationships, institutions, norms, and rule. (link)Social explanations derive their force from empirical research into the nature of the actor, the nature of the locally embodied social environment, and the processes of aggregation through which actions by multiple actors coalesce into social outcomes. The explanation satisfies us when it demonstrates the pathways through which individuals, constituted as they are found to be, located in institutions of the sort described, contribute to collective outcomes of the kinds described.