Wheeler M (2010) In Defense of Extended Functionalism. In: Menary R (ed.) The Extended Mind. Life and Mind series: Philosophical Issues in Biology and Psychology. Cambridge, MA, USA: MIT Press, pp. 245-270. http://mitpress.mit.edu/books/extended-mind
First paragraph: According to the extended cognition hypothesis (henceforth ExC), there are conditions under which thinking and thoughts (or more precisely, the material vehicles that realize thinking and thoughts) are spatially distributed over brain, body and world, in such a way that the external (beyond-the-skin) factors concerned are rightly accorded fully-paid-up cognitive status. According to functionalism in the philosophy of mind, "what makes something a mental state of a particular type does not depend on its internal constitution, but rather on the way it functions, or the role it plays, in the system of which it is a part" (Levin 2008). The respective fates of these two positions may not be independent of each other. The claim that ExC is in some way a form of, dependent on, entailed by, or at least commonly played out in terms of, functionalism is now pretty much part of the received view of things (see, e.g., Adams and Aizawa 2008; Clark and Chalmers 1998; Clark 2005, 2008, this volume a, b, forthcoming; Menary 2007; Rupert 2004; Sprevak manuscript; Wheeler forthcoming). Thus ExC might be mandated by the existence of functionally specified cognitive systems whose boundaries are located partly outside the skin. This is the position that Andy Clark has recently dubbed extended functionalism (Clark 2008, forthcoming; see also Wheeler forthcoming).