Abstract

The hypothesis of the Extended Cognition (ExCog), formulated by Clark and Chalmers (1998), aims to be a bold and new hypothesis about realisers of cognitive processes. It claims that sometimes cognitive processes extend above the limits of the skin and skull and include chunks of the environment as their partial realisers. One of the most pursuasive arguments in support of this assertion is the famous “parity argument” which calls upon functional similarities between extended cognitive processes and relevant internal processes. This very kind of reasoning gave rise to several arguments against ExCog by way of comparing it to functionalism about the mental, which conclude that ExCog must be trivial, radical or unjustified. In this paper ExCog and the underlying parity principle will be defended against four different kinds of “functionalist” arguments. It will be argued that ExCog can be justified as a special form of functionalism, that it is not trivial nor entailed by the known versions of functionalism, and that the accusation of it being too radical is unwarranted.