Abstract

For more than one decade, Andy Clark has defended the now-famous extended mind thesis, the idea that cognitive processes leak into the world. In this paper I analyse Clark’s theoretical justification for the thesis: explanatory simplicity. I argue that his way of justifying the thesis leads into contradiction, either at the level of propositional attitude ascriptions or at the theoretical level. I evaluate three possible strategies of dealing with this issue, concluding that they are all likely to fail and that therefore, as regards explanatory simplicity, the burden of proof is on Clark’s side. The paper divides into two main sections: in “Simplicity and Coherence”, I define the two concepts that are important in this context (simplicity and explanatory coherence). In “How to Cope with Coherence”, these two concepts are applied to the central thought experiment, the Inga/Otto case. It will be shown that justifying the extended mind thesis by reference to simplicity may cause trouble, because ‘extended’ behavioural descriptions are likely to yield rather complicated explanations