The thesis of methodological individualism in social science is commonly divided into two different claims-explanatory individualism and ontological individualism. Ontological individualism is the thesis that facts about individuals exhaustively determine social facts. Initially taken to be a claim about the identity of groups with sets of individuals or their properties, ontological individualism has more recently been understood as a global supervenience claim. While explanatory individualism has remained controversial, ontological individualism thus understood is almost universally accepted. In this paper I argue that ontological individualism is false. Only if the thesis is weakened to the point that it is equivalent to physicalism can it be true, but then it fails to be a thesis about the determination of social facts by facts about individual persons. Even when individualistic facts are expanded to include people's local environments and practices, I shall argue, those still underdetermine the social facts that obtain. If true, this has implications for explanation as well as ontology. I first consider arguments against the local supervenience of social facts on facts about individuals, correcting some flaws in existing arguments and affirming that local supervenience fails for a broad set of social properties. I subsequently apply a similar approach to defeat a particularly weak form of global supervenience, and consider potential responses. Finally, I explore why it is that people have taken ontological individualism to be true.

This paper sets out an organizing framework for the field of social ontology, the study of the nature of the social world. The subject matter of social ontology is clarified, in particular the difference between it and the study of causal relations and the explanation of social phenomena. Two different inquiries are defined and explained: the study of the grounding of social facts, and the study of how social categories are “anchored” or set up. The distinction between these inquiries is used to clarify prominent programs in social theory, particularly theories of practice and varieties of individualism.

pickup baseball teams, research groups, musical groups, pop bands, symphony orchestras, marching bands, social classes, races, genders, demographic cohorts, psychographic cohorts, geographic cohorts, corporate marketing groups, corporate HR groups, boards of directors, rioting mobs, marching platoons, processions of mourners,… we could go on and on, listing kinds and sub-kinds.A chaotic list like this cries out for order and explanation. What, if anything, do social groups have in common? What sorts of entities are social groups, how are they individuated, and what are their persistence and identity conditions? How are they set up, and what do they do for us? How can we best construct a classification or typology of groups?In approaching these questions in this article, I have two aims. First is to challenge the idea that they have simple answers. There seems to be a powerful drive among theorists to unify and simplify the endless diversity and variation among kinds of groups. Many people, for instance, try to draw simple lines between social groups and mere collections of people, or else to divide groups into a few fundamental varieties. 1 I hope to show that this is a non-starter. Too much faith in parsimony misleads an investigation of social groups from the outset.The second aim is to present a practical and systematic approach for analyzing and explaining the nature of groups. Instead of thinking mainly about the umbrella category of social groups, I propose to investigate their details from a "micro" or "bottom-up" perspective, constructing profiles of the metaphysical features of groups of specific kinds. I propose that we can characterize any given kind of social group with four complementary profiles:1. Its "construction" profile. This profile characterizes how groups of a * I am grateful to Katherine Ritchie, Amie Thomasson, and Robin Dembroff, to participants in the 2016 ENPOSS, CollInt, and MANCEPT conferences, and to three anonymous referees, for valuable comments and suggestions.

It is often seen as a truism that social objects and facts are the product of human intentions. I argue that the role of intentions in social ontology is commonly overestimated. I introduce a distinction that is implicit in much discussion of social ontology, but is often overlooked: between a social entity's "grounds" and its "anchors." For both, I argue that intentions, either individual or collective, are less essential than many theorists have assumed. Instead, I propose a more worldly -and less intellectualist -approach to social ontology.It is often seen as a truism that social objects (such as dollars) and social facts (such as that the Federal Reserve is raising interest rates) are the product of human intentions. As distinct from natural objects and facts, which exist or are the case independently of us, social objects and facts exist in virtue of our having attitudes toward the world, attitudes usually taken with some practical aim in mind.This postulate is a basic building-block of prevailing theories of social ontology. Lynne Baker, for instance, explains that artifacts "are objects intentionally made to serve a given purpose."

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