Internalism

Internalism is a family of positions in philosophy that locates essential normative, epistemic, or semantic determinants within the subject’s own mental life rather than in external features of the world. The term is used across several domains, with related yet distinct claims.

In epistemology, internalism about justification holds that what justifies a belief is ultimately accessible to the thinker’s own conscious states—such as perceived evidence, introspection, or reasons that appear to the agent. Externalism, by contrast, holds that justification can depend on factors outside the subject’s awareness or control, such as the reliability of belief-forming processes or causal connections to the truth.

In ethics, internalism about reasons asserts that if there is a normative reason for an agent to act, that reason is in some sense part of the agent’s motivational framework and must be accessible to them. Externalism about reasons contends that reasons can exist independently of an agent’s own psychology, potentially arising from social or external considerations.

In philosophy of mind and language, internalism about content or meaning claims that the content of mental states is determined by internal conditions—what is in the subject’s own mind—whereas externalist theories tie content to external factors like the environment, community, or causal relations.

Debates around internalism versus externalism vary by domain and are ongoing. Proponents argue for the primacy of interior factors such as accessible evidence, motivation, or mental content, while critics caution that environments and external relations can play indispensable roles in justification, justification, meaning, and action.