CONCEPT
The Parity Principle
Clark and Chalmers's argumentative engine: if a process in the world functions as a cognitive process would inside the head, it is cognitive regardless of its location.
The parity principle is the load-bearing claim of the extended mind thesis. Formulated by Clark and Chalmers in 1998, it holds that the location of a cognitive process — inside the skull or outside it — is irrelevant to its cognitive status. What matters is functional role: what the process does, how it contributes to the cognitive life of the agent, whether it plays the kind of role that internal cognitive processes typically play. For twenty-seven years the principle was tested against modest external components. The arrival of large language models, which perform sophisticated cognitive functions at scale, has made the principle's verdict more consequential and more contested than at any previous moment.
In The You On AI Field Guide
The principle operates as a rebuttal to what Clark calls bioprejudice — the assumption that cognition must occur in biological tissue to count as cognition. If the cognitive status of a process depended on its substrate, then the principle would fail trivially. But