Active Externalism

Active externalism is the position, advanced by David Chalmers and Andy Clark in their 1998 paper The Extended Mind, that cognitive processes and mental states can extend beyond the boundary of the brain and skull to include external objects and environments. When an object in the environment plays the same functional role that an internal memory or cognitive process would otherwise play, active externalism holds that object to be part of the cognitive system — not a mere tool used by a bounded mind, but a literal component of it.

The paradigm case is the notebook: if a person with a failing memory habitually consults a notebook and uses its contents in exactly the way they would use remembered information, the notebook is — on this view — part of their cognitive system. Removing it would be like damaging their memory, not like losing a peripheral device.

Active externalism operates entirely at the functional level — the level of causal role and information availability. It is not a theory of phenomenal consciousness. Whether the extended cognitive system is also the locus of qualitative experience — whether moving the notebook extends the experiential subject as well as the cognitive system — is a question Clark and Chalmers did not answer and perhaps did not intend to raise. Critics note that this leaves a puzzle: the extended mind thesis may be true at the functional level while leaving the hard problem of consciousness precisely where it was. What is extended, on this account, is the boundary of cognition, not the boundary of experience.