Social determinism is the hypothesis that social interactions and constructs alone determine individual behavior (as opposed to biological or objective factors).

Consider certain human behaviors, such as having a particular sexual orientation, committing murder, or writing poetry. A social determinist would look only at social phenomena, such as customs and expectations, education, interpersonal interactions, and memes, to decide whether or not a given person would exhibit any of these behaviors. They would discount biological and other non-social factors, such as genetic makeup, the physical environment, etc. Ideas about nature and biology would be considered to be socially constructed.

Social determinism is the opposite of biological determinism.