Methodological individualism is the doctrine that large-scale social events and conditions, such as wars, social customs, economic recessions, the crime rate, and the state, should be explained or understood wholly in terms of the beliefs, intentions, attitudes, and actions of individual people. It is “methodological” in the sense that it indicates how social scientific inquiry ought to proceed; the “individualism” stems from its insistence that social scientific explanations should, at least ultimately, involve only facts about individual agents. Methodological collectivism or holism, in contrast, contends that at least some social phenomena can be explained only at a macroscopic or holistic level.
Methodological individualism was at issue in many high-profile disputes in sociology, psychology, economics, and the philosophy of history during the late 19th and 20th centuries. ...
Kolb, R. W. (2008). Methodological individualism. In Encyclopedia of business ethics and society (Vol. 1, pp. 1383-1384). SAGE Publications, Inc., https://www.doi.org/10.4135/9781412956260.n515