Some social theorists have treated social constructs as unified macro-entities with their own causal powers. Structuralist theories maintain things like "capitalism causes people to value consuming more than family time" or "democracy causes social cohesion." Likewise, some theorists have held that moral systems and cultures cause distinctive patterns of behavior--"Confucian societies produce cohesive families." Each of these claims places a large social entity in the role of a causal factor.
Is this a coherent way of talking? Can large structures and value systems exercise causal influence? The problem here is that statements like these look a lot like "action at a distance". We are led to ask: HOW do capitalism, democracy, or Confucianism influence social outcomes? In other words, we want to know something about the lower-level mechanisms through which large social facts impact upon behavior, thereby producing a change in social outcomes. We want to know something about the "microfoundations" of social causation.
One point seems obvious--and yet it is often overlooked or denied. Social behaviors are carried out by individuals, and individuals are influenced only by factors that directly impinge upon them (currently or in the past). Consider a particular voter's process of deciding to support particular candidate. This person experienced a particular history of personality formation--a particular family, a specific city, a work history, an education. So the person's current political identity and values are the product of a sequence of direct influences. And at the moment, this socially-constructed person is now exposed to another set of direct influences about the election race---newspapers, internet, co-workers' comments, attendance at political events, etc. In other words, his or her current political judgments and preferences are caused or influenced by a past and current set of experiences and contexts.
This story brings in social factors at every stage--the family was Catholic, the city was Chicago, the work was a UAW-organized factory. So the individual is socially influenced and formed at every stage. But here is the important point: every bit of that social influence is mediated by locally experienced actions and behaviors of other socially formed individuals. "Catholicism", "Chicago culture", and "union movement" have no independent reality over and above the behaviors and actions of people who embody those social labels.
This perspective is sometimes called methodological individualism. I prefer to call it methodological localism. We never lose the social in this story. But it is always a locally embodied social, conveyed through pathways that directly impinge upon the socially constituted person. It is then a subject of real sociological interest, to discover the pathways and variations through which the large social entities are embodied. And in this way we avoid the error of "reification" of the large social entity.