If it turns out that there are irreducible mechanisms (nonlocalizable or nondecomposable) at the highest levels within the brain then, because it is at roughly the same scale and there are many interactions at that shared level, it may be necessary to bring in the external environment as part of the cognitive mechanisms in question or at least as essential background for their function. (Chemero & Silberstein, 2008, p. 8).I'm not getting the thinking here. So, suppose there are some irreducible (cognitive?) mechanisms at the highest levels in the brain. Why would this make it necessary to bring in the external environment as part of the cognitive mechanisms in question? I'm not getting it. C&S do hedge and throw in "it may be necessary", but still why may this be necessary?
There are other considerations given later, such as that mechanisms often function only in certain contexts, but this is a separate matter from the irreducibility consideration cited above.
Chemero, A., & Silberstein, M. (2008). After the Philosophy of Mind: Replacing Scholasticism with Science. Philosophy of Science, 75, 1-27.