Common-sense functionalism and the extended mind

The main claim of this paper is that Andy Clark's most influential argument for ‘the extended mind thesis’ (EM henceforth) fails. Clark's argument for EM assumes that a certain form of common-sense functionalism is true. I argue, contra Clark, that the assumed brand of common-sense functionalism does not imply EM. Clark's argument also relies on an unspoken, undefended and optional assumption about the nature of mental kinds—an assumption denied by the very common-sense functionalists on whom Clark's argument draws. I also critique Mark Sprevak's reductio of Clark's argument. Sprevak contends that Clark's argument does not merely entail EM; it entails an extended mind thesis so strong as to be absurd. He goes on to claim that Clark's argument should properly be viewed as a reductio of the very common-sense functionalism on which it depends. Sprevak's argument shares the flaw that afflicts Clark's argument, or so I claim.