In this paper we develop a novel argument against the extended mind hypothesis. Our argument constitutes an advance in the debate, insofar as we employ only premises that are acceptable to a coarse-grained functionalist, and we do not rely on functional disanalogies between putative examples of extended minds and ordinary human beings that are just a matter of fine detail or degree. Thus, we beg no questions against proponents of the extended mind hypothesis. Rather, our argument consists in making use (...) of the following necessary condition on holding a belief for a reason: To believe something for a reason, one must come to believe it in virtue of attitudes that epistemically rationalize the belief that is formed, and one must come to believe in virtue of the fact that these attitudes epistemically rationalize the new belief. We show that many external objects that defenders of the extended mind hypothesis have claimed are beliefs cannot constitute a belief had for a reason, as they necessarily fail to satisfy the necessary condition. Our first thesis, then, is that beliefs had for reasons cannot be extended in the most interesting way specified by the extended mind hypothesis. Furthermore, if we add to our argument the premise that every token belief is something that could have been had for a reason, we can derive the stronger thesis that no beliefs can be extended in this way. (shrink)