Internalism and externalism are two opposite ways of integration of explaining various subjects in several areas of philosophy. These include human motivation, knowledge, justification, meaning, and truth. The distinction arises in many areas of debate with similar but distinct meanings. Internal–external distinction is a distinction used in philosophy to divide an ontology into two parts: an internal part concerning observation related to philosophy, and an external part concerning question related to philosophy.

Internalism is the thesis that no fact about the world can provide reasons for action independently of desires and beliefs. Externalism is the thesis that reasons are to be identified with objective features of the world.