A few days ago, I noted that, in his Extended X manuscript, Mike Wheeler is on board with the idea that advocates of extended cognition should provide what is often loosely referred to as a "mark of the cognitive". This is some account of what differentiates cognitive processes from non-cognitive processes. Mark Rowlands (2009) also supports a role for a "mark of the cognitive" in making the case for extended cognition.
In his recent NDPR review of Rupert's Cognitive Systems and the Extended Mind, however, Rob Wilson apparently rejects this move:
Thus, we need a principle of demarcation that delineates mere causes from genuine constituents of cognition.
There are two short but basic questions to pose here. First: why? Second, one that I have picked up at occasional postmodernist seances: who are “we”? Take them in reverse order. Precisely who needs this kind of principle of demarcation? Surely not practicing cognitive scientists, in part because they seem to have gotten along perfectly well without one until now. Philosophers? Well, not philosophers who take one of the chief lessons of the failure of logical positivism in the philosophy of science, the collapse of the analytic-synthetic distinction along Quinean lines in the same, and the limitations of conceptual analysis to be a deep suspicion of the search for such principles.
In The Bounds of Cognition, Adams and I tired to forestall these challenges to a mark of the cognitive at pp. 84, 86-87.
We think it is completely correct to observe that vast areas of cognitive psychological research can proceed without a definition or theory of cognition and we don’t propose to change that. This is just like the observation that many research projects in biology can proceed without a definition or theory of what life is. One can surely explore the mechanisms of mitosis and meiosis, for example, without a theory or definition of life. One can surely even attempt to reconstruct much of the evolutionary “tree of life” with a definition or theory of what life is. The point to observe, however, is that even though many projects in psychology can proceed without a theory of the cognitive, just as many projects in biology can proceed without a theory of life, not all projects are like this. In particular, the hypothesis of extended cognition would seem not to be such a project. If one maintains that, say, the brain, body, and environment sometimes forms a chaotic dynamical system, one would naturally expect an explanation of what a chaotic dynamical system is. Similarly, if one maintains that the brain, body, and environment sometimes gives rise to an extended cognitive process, one expects a theory of what cognition is. Indeed, the more radical the proposal about the bounds of cognition, the greater the need there is for such a theory. Consider how things might go in biology. It is not so surprising to be told that single-cell organisms are alive. It is somewhat more surprising to be told that viruses are alive. One might, at that point, wonder what is meant by being alive. But, faced with the assertion that crystals are alive, one surely wants to hear some account of what is meant by saying that crystals are alive. So it is with cognition. For most purposes, cognitive psychologists can get by without much in the way of a theory of what cognition is. But, faced with the assertion that cognitive processes extend into pencils and paper, one should want to know what conception of cognitive processes is in play. (pp. 86-87).
Evidently, the dispute must be joined by a substantive theory of the cognitive. This is why we offer the conjecture that cognitive processes involve non-derived representations that are embedded within (largely unknown) cognitive mechanisms. This is not a definition of the cognitive, let alone a stipulative definition of the cognitive. It is a theory that we think is implicitly at work in a lot of cognitive psychological research. Cognitive psychologists have not, in general, definitively established what mechanisms are at work in cognitive processing, but they generally assume that cognitive mechanisms exist and that they are discoverable through clever experimental techniques. We very briefly described just the tip of the iceberg of research there is on memory, leaving aside the vast literature on such topics as linguistic processing, attentional processing, and reasoning. (p. 84).