Over the years I've continued to advocate for the position of ontological individualism -- the idea that social entities, powers, and conditions are all constituted by the actions, thoughts, and mental frameworks of individual human beings, and nothing else. I'm no longer entirely confident that this is an adequate view of social ontology, because I also maintain that doing good social science requires researchers to work with a rich theory of the social actors who constitute the "substrate" of the social world. In particular, I maintain that we need to view social actors as "socially constituted" and "socially situated". This means, fundamentally, that individuals develop into actors through interaction and exposure with the communities and institutions with which they interact from childhood to adulthood -- thus coming to possess various features of motivation, cognition, and reasoning on the basis of which they act in the social world. Further, individuals exist within institutional, cultural, and normative settings that establish constraints, resources, opportunities, and limitations on their actions. Actors are "socially situated" in ways that profoundly affect their actions.
The diagram above represents a flat social ontology, with individuals and social entities in a range of locally instantiated relationships. As the arrows indicate, influence flows in all directions, from actors to structures and from structures to individual actors and between both structures and actors. (Here is a post from 2015 that considers the logic of a "flat social ontology"; link.)
So if individual actors depend on the local and historically particular social environments in which they exist -- environments that are themselves embodied by other actors -- then in what sense can we legitimately say that the individual level is more fundamental than the social level?
Two ideas seem to be true, and they are in tension with each other. On the one hand, most views about "priority of individuals" over social facts are unsupportable. Individuals are not temporally prior to social relations and influences; individuals are not causally prior to social influences (since each actor is formed and constrained by social relationships and practices); individuals cannot be characterized in terms that avoid "social" characteristics (semantic priority); and individuals are not explanatorily prior to social facts (since social facts must be invoked to describe and explain the individual's mentality and action).
But likewise, social structures, practices, and institutions are not strictly prior to individuals. Social influences on individuals at a time depend upon the actions, thoughts, and relationships of an indefinitely large group of individual actors. That is to say that social arrangements work through the actions and mentalities of the individuals who make them up. Further, social structures are not strictly speaking causally prior to individuals in any absolute sense -- it is not the case that social structures determine the actors, and in fact later iterations of social structures and institutions are changed as a result of the actions and non-actions of the actors themselves.
So it seems clear that individuals are shaped by social realities (practices, institutions, normative systems) and social realities are constituted, maintained, and changed by individuals. We cannot separate them into separate and independent causal factors.
This suggests that neither "individualism" nor "holism" will do as a basis for social ontology. Neither individual mentality and action nor the dictates and constraints of social facts persist by themselves. Instead, social actors depend upon existing social relationships and arrangements, and social facts depend upon individual actors which carry and transform them. We need to conceive of both individual actors and social arrangements as part of a single, iterative and diverse process of change and continuity. And, unfortunately, the label of ontological individualism does not capture the fullness of this set of processes.
Other theorists have tried to solve this problem. Anthony Giddens addresses this complexity through his effort to undermine the strict distinction between agent and structure. He challenges the framework itself -- the idea that "agents determine structures" and the idea that "structures determine agents". He introduces a new term to capture the complexity of the relationship between actors and structures, the idea of structuration. His 1979 collection of essays, Central Problems in Social Theory: Action, Structure, and Contradiction in Social Analysis, provides a statement of some of his views. Here is how he frames his core concern in a key essay, “Agency, Structure”:
The principal issue with which I shall be concerned in this paper is that of connecting a notion of human action with structural explanation in social analysis. The making of such a connection, I shall argue, demands the following: a theory of the human agent, or of the subject; an account of the conditions and consequences of action; and an interpretation of ‘structure’ as somehow embroiled in both those conditions and consequences. (49)
Giddens faults much of sociology for having failed to conceptualize the social-structural context with sufficient nuance. He finds, for example, that Durkheim’s efforts to provide theoretical resources for describing the “external or objective” character of society were inadequate (51). The problem is that neither individualists nor structuralists have succeeded in expressing the inherent interdependence of the two poles. Give primacy to structures and the agents are “dopes” — robots controlled by structural conditions. Give primacy to individuals, and structures and institutions seem to disappear. Giddens' own view is that the two poles of structure and agency must be considered from within a common formulation:
I shall argue here that, in social theory, the notions of action and structure presuppose one another; but that recognition of this dependence, which is a dialectical relation, necessitates a reworking both of a series of concepts linked to each of these terms, and of the terms themselves. (53)