externalism, the view of the mental states of an individual that they (the mental states) may have, as their physical SUPERVENIENCE bases, something of greater spatiotemporal extent than the individual himself or herself. Alternately, any view that holds that either mental states themselves or the factors determinative of a state’s CONTENT, extend beyond the physical boundaries (skull and skin) of the individual who possesses the mental states. This latter construal of externalism allows us to sort externalistic theories into two sorts: VEHICLE externalism and content externalism (see CONTENT/VEHICLE DISTINCTION). Another way of sorting externalistic theories, a way that cuts across the content-externalism vs. vehicle-externalism division, sorts externalistic theories in terms of whether they apply to QUALIA (see CONSCIOUSNESS, PHENOMENAL) or instead to only non-phenomenal aspects of the mind, e.g., allegedly non-phenomenal intentional states such as beliefs (see BELIEF). The four kinds of externalism generated by these two cross-classifying distinctions (content-vehicle, intentional-phenomenal) may be usefully labeled as follows: (1) intentional content externalism, (2) intentional vehicle externalism, (3) phenomenal content externalism, and (4) phenomenal vehicle externalism.
Intentional content externalism is probably the most discussed in the literature. One version of it may be described as follows. Individuals that have the same intrinsic physical properties may nonetheless diverge in the content of the thoughts they express when they say ‘this is water’ if the substance called ‘water’ in their respective environments is chemically distinct (H2O in the one and XYZ in the other). Content viewed as the intentional content externalist views it is oft described as “WIDE CONTENT”. (See SWAMPMAN; TWINEARTH; XYZ.)
One version of intentional vehicle externalism has been defended by Andy Clark and David CHALMERS under the heading of the “extended mind hypothesis” (see EXTENDED MIND).
Contemporary defenders of phenomenal content externalism, such as Michael Tye and Fred DRETSKE, identify qualia with the contents of certain kinds of MENTAL REPRESENTATION and then are led to externalistic conclusions via an embrace of an externalistic theory of content such as a version of the CAUSAL THEORY OF CONTENT or TELEOSEMANTICS. Such phenomenal content externalists also embrace FIRST-ORDER REPRESENTATIONALISM about CONSCIOUSNESS as well as the thesis of that experience is transparent (see TRANSPARENCY (OF EXPERIENCE)).
Phenomenal vehicle externalism is perhaps the least popular of the four kinds of externalism so far. But it does have advocates, notably Alva Noë and Susan Hurley. Advocates of this approach frequently emphasize the role of EMBODIMENT in structuring our PHENOMENOLOGY.
See also INTERNALISM.