Phenomenal fact fight.
In this, the second post in the series, “Swamp Mary Semantics: A Case for Physicalism Without Gaps,” I spell out some further crucial details of the central thought experiment.
Given the trouble I claim to be raised for gappy physicalists by Swamp Mary, it is natural to consider possible grounds that gappy physicalists might have for rejecting as impossible one or more aspects of the Swamp Mary scenario.
There seems to be no basis for gappy physicalists to deny that a being can be intrinsically identical to post-release Mary and never have experienced a red quale. That such a complicated entity can spring into being fully formed by quantum accident is of course highly improbable, but it is not impossible. Further, possible events of such high improbability are the bread and butter of gappy physicalists relying, as much as they do, on the conviction that there could be a physically omniscient yet phenomenally ignorant Mary.
Someone who finds it easy to grant the possibility of a person forming Swamp-style might nonetheless resist granting the possibility of a being physically intrinsically identical to post-release Mary who, the Swamp being, lacks a red quale. A useful means for overcoming such resistance is to imagine that post-release Mary has been knocked out with a general anesthetic. It is natural to assume that a person under a general anesthetic has no experiences (otherwise, general anesthesia is misnamed). Thus, if Swamp Mary pops into existence intrinsically physically identical to generally anesthetized post-release Mary, then Swamp Mary does not at that time have a red quale.
But would a generally anesthetized Swamp Mary, lacking a red quale, nonetheless know what it’s like to have a red quale? Prima facie, Swamp Mary does, since, despite being generally anesthetized, post-release Mary does. Anesthetics are not, generally, amnestics, and Mary, having learned what it’s like to see red, need not forget it or anything else when she’s put under.
Of course, to assume that Swamp Mary has phenomenal knowledge of a quale she’s never yet experienced is to assume that phenomenal knowledge does not supervene on historical relations to particular past events. Call such an assumption ahistoricism and its negation, historicism. Might gappy physicalists dodge Swamp Mary by insisting on historicism about phenomenal knowledge? This is a difficult question to assess, but it helps to look at the relative merits of historicism as applied to other kinds of knowledge.
Probably the cases most crying out for historicism are cases wherein the knowledge in question concerns putative particular past events concerning the knower herself. It is quite strained to say of Swamp Mary that she knows what happened to Mary nine years ago even though she may have an internal state physically similar to a state that Mary is in when Mary correctly remembers what happened to her nine years ago. There is no nine years ago for Swamp Mary, and her state is a mere quasi-memory.
We might summarize by saying that the case for historicism is strongest when it is applied to putative knowledge that is both historical and egocentric. Crucially, knowledge of historical egocentric facts involves knowledge of particulars, knowledge of particular past events concerning a particular person.
When we shift our attention from knowledge of particulars to knowledge of generalities, the intuitive pull of historicism weakens considerably. While it may have a high degree of plausibility to claim that a newly-minted Swamp-being cannot count as retaining first-hand knowledge of autobiographical events from nine years ago, it is comparatively less plausible to claim that the same Swamp being can’t know that nine years ago is five years ago plus four years ago. Pieces of knowledge that have a high degree of generality, like that twice four is eight and that everything is self-identical, are harder to deny attributing to our Swamp doubles.
The question to ask, then, of phenomenal knowledge, since we are interested in whether Swamp Mary really has any, is whether phenomenal knowledge is more appropriate to think of as general or particular. And here I think that a stronger case can be made for the generality rather than the particularity of phenomenal knowledge. As pointed out in Mandik (2001), the common intuition regarding Mary is that she learns not only what it is like for her to see red, but she is also in a position to grasp what it must be like for others to see red as well.
Of course, it is not unheard of for philosophers to take a very hard line on Swamp beings. Dretske (1995), for instance defends an etiological teleosemantic version of representationalism about qualia wherein it’s a requirement on having any conscious experiential content that a creature have a certain evolutionary history. On a Dretskean account, Swamp Mary, even un-anesthetized and staring at a red rose, wouldn’t have any red qualia and a fortiori, wouldn’t know what it’s like to have red qualia.
Might a gappy physicalist adopt a strong historicism to protect against the threat of Swamp Mary? A problem that arises here seems to be that very strong externalism such as the one that leads to Dretske’s historicism is likely to be inconsistent with Mary’s prerelease phenomenal ignorance (see Dretske (1995, pp. 81-95)) On Dretske’s view, what it’s like to experience red is to be in a state that bears certain historico-evolutionary relations to red surfaces. If Mary knows what surface properties a color-sighted person is historico-evolutionarily related to, then the fact that Mary has never herself entered into such relations is no bar to her knowing what it’s like for a color-sighted person to see red. On Dretske’s view, Mary may lack experiential representations of red surfaces, but this is no bar to her having representations of such surfaces in thought, and it is her thought representations that underwrite her knowing what it is like to have experiences that she has not herself had.
While these remarks about Dretske have been brief, I take them to cast doubt on the prospects of gappy physicalists blocking the threat of Swamp Mary by denying her very possibility.