Mark Sprevak, King's College, Cambridge
January 27th, 2009

This paper considers the main arguments for and against the hypothesis of extended cognition (HEC). HEC says that our cognitive processes can, and often do, extend outside our heads to include objects in the environment like notebooks and computers. Arguments for and against HEC often take the form of inferences to the best explanation (IBEs): the truth or falsity of HEC is justified by its explanatory value to cognitive science. Advocates and critics of HEC have tended to assume that IBE must support either the truth or falsity of HEC. The truth value of HEC should be decided by whether HEC makes a positive or negative explanatory contribution to cognitive science. Little consideration has been given to a third option: that this form of explanatory-value reasoning may not even be a warranted form of inference in this case. In this paper, I argue that, on close analysis, use of IBE is not valid in these contexts, and that if HEC is to supported or criticised, it should be done in other ways.