Swamp Thing About Mary at Philosophy Sucks!

Richard Brown has posted a thoughtful discussion of my recent Swamp Mary talk: Swamp Thing About Mary at Philosophy Sucks!

Richard writes:

I suggested in discussion that Pete was running over the distinction between ‘knowing what it is like’ in the general sense, and ‘knowing what it is like FOR one’. To know what it is like for one too see red requires that one have, or be able to recall, a red experience and to be able to say, so to speak, to one’s self ‘this is what it is like to see red’. To know what it is like in the generic sense is to know what it is like to see red in the way that pre-release Mary is typically thought of by the type-b physicalist. She can know a lot about what it is like to see red. She can know that it is more like seeing something pink than it is like seeing blue, and all other kinds of facts. But intuitively she doesn’t know what it is like for her to see red. Once we have this distinction in mind we no longer have a problem with Swamp Mary. Swamp Mary knows what it is like in the generic sense, in just the same way as pre-release Mary, but she does no know what it is like for her to have the experience, again just like pre-release Mary.

Here are my main thoughts on this right now:

Here are two problems I have with the alleged distinction between generic phenomenal knowledge and for-me phenomenal knowledge.

The first problem is something I was trying to articulate during the Q&A in terms of a corner of room that you’ve never been in before. You’ve been in every part of the room except that corner, and the corner is completely visible from the rest of the room. The only knowledge that you lack by necessity of having never been in that corner is the knowledge indexically expressible as “I’m here now”. But aside from this thin and trivial sense that there’s a piece of knowledge you lack prior to arriving in that corner, it doesn’t look like there’s anything substantial that you couldn’t have known already about what’s going on there. It’s hard to see the hubub about the experience requirement as just reducing to this fact about indexicals.

The second problem is something I don’t think we’ve talked about much. It has to do with the generality of the experience requirement. I think a lot of people who are attracted to the experience requirement do *not* think that it generalizes to all experience. So, for example, if someone had seen all shades of gray except for 45% gray, it’s implausible that they would need to experience that shade in order to know what it’s like to experience it. The experience requirement is intuitively powerful for examples like red. But not so much for the missing shade of gray. So what’s the second problem? It’s the problem of supplying an account of what knowing what it’s like FOR one in such a way that you don’t wind up with the fully generalized experience requirement. Now, if the account of for-me phenomenal knowledge just is the indexical thing, then you wind up with an implausibly generalized experience requirement where there’s no significant difference between never having seen red before and never having seen 45% gray before.

New Swamp Mary Paper, Talk

On Friday October 8, I'm giving my talk "Swamp Mary Semantics: A Case for Physicalism Without Gaps" at the CUNY Grad Center (1-3pm room 7102). Here's a link to the paper: link.

The Feeling of Being Blogged About

Some of my stuff has been recently blogged about elsewhere and vanity compels mention here. Richard Brown at Philosophy Sucks has been blogging on my and Josh Weisberg's Type-Q Materialism here: Am I a Type-Q Materialist?

Jason Streitfeld at Spectre of Reason has been blogging on my Swamp Mary's Revenge and Swamp Mary Semantics here:

• Deviant Phenomenal Knowledge
• Can Swampkinds be Deviants?
• Swamp Deviants, Part II

My Swamp Mary paper is now in print

My Swamp Mary paper is now in print. Here's the info:

Mandik, P. (2010). Swamp Mary’s Revenge: Deviant Phenomenal Knowledge and Physicalism. Philosophical Studies, 148(2), 231-247.

http://www.springerlink.com/content/l07pw010561jx1m5/

Attack of the Boltzmann Brains!

Yikes! Swamp-brain supervillians (@Cosmic Variance):

Attack of the Boltzmann Brains!: "

Swamp Draft Online

Thanks, all of you who read and commented on the serialization of my new Swamp Mary draft. Here it is as a single pdf: "Swamp Mary Semantics: A Case for Physicalism Without Gaps"

Bandwidth and Storage in the Human Biocomputer

One ballpark estimate of the memory capacity of the human brain is that it is in the range of 10^13 - 10^17 bits (Tipler, 1995). These numbers are much too large for current purposes if we assume that not all of the brain’s memory is in the service of concepts. A smaller number may be arrived at by assuming that concepts are restricted to pre-frontal cortex (PFC). The volume percentage of PFC to the whole brain is 12.51 (McBride, Arnold, & Gur, 1999) and thus we arrive at a reduced memory capacity estimate in the ballpark of 10^12 bits.

Is what Mary knows while staring at red for the first time simply too much information than can be squeezed into a memory store of 10^12 bits? It seems not.

An early estimate of the bandwidth of the human eye for color vision is 4.32 x 10^7 bits/sec (Jacobson, 1950, 1951). A more recent estimate is 10^6 bits/sec (Koch et al., 2006) aka a megabyte per second (1MB/sec). The computer-savvy reader may already have an intuitive grasp of 1MB/sec. The Wikipedia entry for “megabyte” (accessed July 24, 2008) tells us that a megabyte of data is roughly equivalent to a 1024x1024 pixel bitmap image with 256 colors (8 bpp color depth), 1 minute of 128 kbit/s MP3 compressed music, or a typical book volume in text format (500 pages × 2000 characters).

Assuming Mary has to stare at a red object for a full second to know what it’s like to see red, our lowest estimate of human memory capacity is still an order of magnitude higher than what comes into her eye during that second. (And that’s assuming that Mary has a normal-sized human PFC. Physically omniscient Mary may likely have a bigger brain than normal.) From a purely information-theoretic perspective, giving her bigger lobes would make it even easier to know what it’s like.

So, from an information-theoretic perspective, Mary’s memory capacity is easily large enough for phenomenal knowledge to be conceptual. But the information has to get in there somehow and maybe color vision is the only pipeline fat enough to do the trick. Unfortunately for the defender of the Experience Requirement, there’s no purely information theoretic basis for her position.

Jacobson (1950, 1951) gives a bandwidth estimate of 4.32 x 10^6 bits/sec for the eye for black and white vision and an estimate of 9,900 bits/sec for the bandwidth of the human ear. Continuing with our assumption that Mary would require a full second to gain, via color vision, knowledge of what it’s like to see red, then the very same amount of information can be acquired by a color blind person in 10 seconds and a blind person acquiring the information auditorially would need a full 73 minutes. Reducing our estimate of how long Mary needs to a tenth of a second means that the color blind could acquire that information in about a second and the fully blind in seven minutes.

(Of course, none of this is to say that, for example, the blind person would be hearing red. But it is to say that she is learning whatever is to be learned by the sighted when they see red. The information acquired about red may enter sensory systems without giving rise to conscious experience.)

The above considerations about bandwidth help us to see why the Experience Requirement may strike so many people as plausible. There is a marked difference between what you can learn in a second and what you can learn in 73 minutes. And it is reasonable to assume that people have an at least rough grasp of the informational capacities of their various sensory systems.

Nonetheless, regardless of whether we interpret Hume’s assertion about what the blind can know about color as a claim about nomological, metaphysical, or logical possibility, the claim receives no support from these information-theoretic considerations. From the information-theoretic perspective it is nowhere near impossible for the blind to acquire information of the presence of redness. They just need a longer time than the sighted to do so.

Previous posts:

1. Swamp Mary Semantics: A Case for Physicalism Without Gaps

2. There’s Something About Swamp Mary

3. Putting the Physicalism in Gappy Physicalism

4. Swamp Mary and the Psychosemantic Challenge

5. Nomological Psychosemantics in the Swamp

6. Descriptive Psychosemantics and Phenomenal Knowledge

7. Can the appearance of a phenomenal-physical gap be explained away?

Can the appearance of a phenomenal-physical gap be explained away?

In the remaining posts of this series I address a question that I think is not addressed frequently enough in the literature. Why do people suppose that there is an epistemic gap? Asked in the context of discussions of Mary, the relevant question to ask is: Why do people suppose that prerelease Mary is phenomenally ignorant?

It is no answer to such a question to say that it is intuitive that prerelease Mary doesn’t know what it’s like to see red. For the next question to raise is: Why is that intuitive? And it is no answer to that question to credit the intuition as being true. The truth of an intuition can’t suffice to explain its intuitiveness. Further, if the above arguments concerning Swamp Mary are sound, the intuition in question is false. I think that in general, if an intuition retains its intuitive pull despite being shown to be false, it helps to have an explanation of the source of the intuitive pull. It is toward such an explanation that the current section is directed.

The intuition under question is a thesis that I will, following an earlier work (P. Mandik, in press),  call the Experience Requirement, “the thesis that, for some experiences at least, and red experiences in particular, knowledge of what it’s like to have such an experience requires that the knower has had or is currently having such an experience.”

In an earlier time, classical empiricism was the grounds for a defense of the Experience Requirement. We see expressions of something very close to the Experience Requirement in the work of Locke and Hume. Here’s Locke from An Essay Concerning Human Understanding : “…we see nobody gets the relish of a pineapple, till he goes to the Indies, where it is, and tastes it.” Here’s Hume from An Enquiry Concerning Human Understanding: “A blind man can form no notion of colours; a deaf man of sounds. ….A Laplander or Negro has no notion of the relish of wine.” Locke and Hume offer the Experience Requirement as a piece of common sense that is supposed to help build their case for their theory of ideas. The thought seems to be that their empiricistic theory of ideas is supported by how well it is able to explain the Experience Requirement: if ideas are made of sensory impressions or copies thereof, then of course “a blind man can form no notion of colour.” 

I have serious doubts about whether the account whereby concepts are composed of sensory impressions or copies thereof will stand up to neuroscientific scrutiny. Though I think Weiskopf (2007) makes a convincing case against the neurophysiological plausibility of this kind of concept empiricism, I will not recount the case or pursue this line further here. Instead, I present considerations that directly target the Experience Requirement. 

One way of formulating a question about the truth of the Experience Requirement is as follows. Is it possible that the informational channels that put normally sighted persons in contact with redness are more capacious than either any other sensory input channels or the human memory systems that constitute our objective conceptual grasp of our inner and outer worlds? When we look to scientific estimates concerning, for example, the bandwidth of human color vision, we find the basis for the following two lines of thought. The first is that we can explain why people may have found the Experience Requirement plausible. The second is that considerations concerning neural bandwidth and storage do not suffice to ground the Experience Requirement’s truth. I develop these lines of thought further in the next post of the series.

Previous posts:

1. Swamp Mary Semantics: A Case for Physicalism Without Gaps

2. There’s Something About Swamp Mary

3. Putting the Physicalism in Gappy Physicalism

4. Swamp Mary and the Psychosemantic Challenge

5. Nomological Psychosemantics in the Swamp

6. Descriptive Psychosemantics and Phenomenal Knowledge

Descriptive Psychosemantics and Phenomenal Knowledge

I have previously argued that gappy physicalists who embrace Swamp Mary cannot account for her satisfaction of psychosemantic criteria along the lines of either quotational, causal, or nomological accounts.

            Let us turn, then, to examine the availability, or lack thereof, to gappy physicalists of a psychosemantics along the lines of Descriptive-isomorphism. It helps to first begin by examining a clear case to which Descriptive-isomorphism is most likely to apply. Suppose that someone, let us call him George, is an otherwise normal human who has never before seen the Japanese flag. Let us suppose that George has normal color vision, and has had a typical range of color experiences including having seen red and white before. Suppose further that George has seen various shapes before, including circles and rectangles. George just has never seen a Japanese flag before. Without showing him one, how can we augment his knowledge to include knowledge of what it would be like to see one? Here the answer seems quite simple. We convey to George a description along the lines of “red circle centered on a white rectangular background.” The adequacy of such a description, according to Descriptive-isomorphism is due chiefly, if not exclusively,  to two factors. The first factor is the flag’s being a structured complex (with the comparative simples being redness, circularity, etc. and structural relations being the having of redness by the circle, the centering of the circle on the rectangle, etc.). The second factor is the description’s being a structured complex allowing it to pick out the parts of the complex and their structural relations to each other. It may perhaps ease subsequent exposition to label these two factors “content complexity” and “vehicle complexity,” respectively.

            Given how Descriptive-isomorphism works for George, it is quite difficult to see why it wouldn’t work just as well for Mary. One of the key suppositions of physicalism is that qualia are ontological complexes of non-phenomenal relative-simples. Thus are qualia in a position to satisfy the first key factor of Descriptive-isomorphism, the content complexity factor.  And Mary is physically omniscient, so there would be no non-phenomenal entity or non-phenomenal relations between entities that would exceed her grasp. Thus are states of Mary in a position to satisfy the second key factor of Descriptive-isomorphism, the vehicle complexity factor. I am aware of no third factor essential to Descriptive-isomorphism, so I’m aware of no basis for the gappy physicalist to embrace Descriptive-isomorphism as the psychosemantics of Swamp Mary’s phenomenal knowledge while maintaining prerelease Mary’s phenomenal ignorance. 

            It’s natural here for the gappy physicalist to try to claim that Mary cannot actually satisfy the vehicle complexity factor of Descriptive-isomorphism. The maneuver I have in mind is to affirm that while Mary is able to represent the phenomenal facts under one description, there is some other description that prerelease Mary is not able to represent the facts under. One way in which this might be put is to say that prerelease Mary knows the facts under a physical description but not under a phenomenal description. It is hard to see, however, what is to distinguish kinds of description here in a way that is also going to be consistent with key tenets of both Descriptive-isomorphism and gappy physicalism.

            Suppose that the relevant difference between the descriptions is thought of as analogous to differences between inter-translatable descriptions from distinct languages. Compare the difference between, for example, the English phrase “white rectangle” and the Pig Latin phrase “itewhay ectangleray”. According to Descriptive-isomorphism, their inter-translatability is due to structural commonalities between the descriptions (or commonalties between structures such as languages or language games that the descriptions are respectively embedded in). What makes them different descriptions isn’t going to be any difference in what they are descriptions of, that is, differences in semantic content, but instead differences in the representational vehicles. (The vehicular differences may, of course, be relational as well as intrinsic.)

How can such vehicular differences suffice for prerelease Mary’s phenomenal ignorance? The suggestion along such lines has to be something like that Mary may be able to get into one kind of state, but not be able to get into another. But note now what the key features of this account of Mary’s prerelease omniscience and ignorance amounts to: her omniscience is due to her having a representation, under some description, of every fact, and her ignorance is due to there being states that she is nonetheless unable to get into. But this is just to give a version of the ability response(Lewis, 1990). And the ability response is a defense of physicalism that is not a gappy physicalism. It is crucial to gappy physicalism to hold that what Mary lacks prerelease is a kind of knowing-that, as opposed to a kind of knowing-how.

Previous posts:

1. Swamp Mary Semantics: A Case for Physicalism Without Gaps

2. There’s Something About Swamp Mary

3. Putting the Physicalism in Gappy Physicalism

4. Swamp Mary and the Psychosemantic Challenge

5. Nomological Psychosemantics in the Swamp