August 14, 2006

Logical supervenience

Anand's Blog 08.06.2006 permalink Consciousness In a previous blog entry, I mentioned that we need a new physicalism that can accommodate experience. This by itself is not a new idea. Beginning with a well known attempt by Roger Penrose and Stuart Hameroff, there have been numerous attempts at just that: a new physicalism that can accommodate experience. Unfortunately, most previous attempts at a new physicalism fall short in my opinion. The reason is that most of them do not take Chalmers' logical supervenience argument very seriously.
That is, the bar has now been raised so high that I think it is fair to dismiss any potential new physicalism if the authors (of the new approach) do not spell out how first person facts are entailed by their approach. (Let's set aside the arguments on whether or not entailment can be achieved.) To put it another way, if experience is logically supervenient on the new physical, the facts of experience can be read off from the more basic physical facts and the relevant laws. That is a tall order. A second rather obvious constraint is that the new physicalism should approach the old physicalism under certain limiting conditions. To put it somewhat vaguely, when the experience-related fundamental facts and laws are subtracted out, one should get our good ole third person physicalism. This is complicated by the fact that third person physics itself is incomplete at the moment.
Looking into our crystal ball, let's hypothesize a finished theory of quantum gravity and a set of supervenience relations that bring the worlds of chemistry and biology into “sync” so to speak with this finished theory. (And let's set aside huge puzzles like the asymmetric direction of time in dissipative dynamical systems versus time symmetry which might remain in the finished theory.) We just assume that there is a finished theory of quantum gravity with the worlds of chemistry, biology being supervenient on it. We take it as a given that the finished theory of quantum gravity will have something like a wavefunction specifying a measure on a set of possibilities on particles, fields and spacetime metrics. In other words, a spacetime metric will emerge from this theory and there may very well be a measure (probability) on it.
We now focus on what must be added to the finished theory of quantum gravity in order to make experience supervenient on it. We cannot glibly add first person facts since that would have no predictive power. Rather first person (and second, fourth person etc.) facts must be “organically” incorporated in the new physics. To move in this direction, we examine dual-aspect theories for clues.This step (of looking for clues in dual-aspect theories) has to be justified. The main justification is as follows. A dual-aspect theory can be cleanly constructed from the finished theory of quantum gravity by positing that some (not all) elements of the physicalist base or some elements logically supervenient on the physicalist base have an interior in which experience can occur.
Qualia occur in the interior and physical dispositions occur on the boundary or occur relationally depending on one's theory of dispositions. From our new physicalism perspective, this is unsatisfactory since the dual-aspect theory assumes what we seek: the generation of experience.The first clue therefore is that, if certain elements in nature have an interior, then qualia can occur in the interior and that's a natural way of separating the third person facts (objectivity) from the first- (subjectivity) and second-person facts (intersubjectivity). So, as a necessary condition for experience, what we need is a physical boundary that separates out certain “parts” of nature from other parts. Qualia can then occur in the interior of the walled off space (or more generally spacetime).
Of course, no qualia need occur and the walled off region can be similar to a black hole which we have no reasons to believe has qualia (though this claim is suspect if Lee Smolin's idea that black holes represent walled off universes is correct.) The boundary need not be present in space and persist for some period of time - rather the boundary could wall off a contiguous region in spacetime. The next clue is concerned with the nature of qualia. Here, we have in mind that there is no reason to believe that most qualia are unmediated. Following Wilfrid Sellars' criticism of the “myth of the given”, we can afford to allow the boundary and other (unspecfied) aspects of creating an interior to condition the qualia occurring in the interior.
So far, we have an admittedly vague notion of a boundary creating process that conditions a certain type of event that forms in the interior (and on the interior boundary wall). We have not discussed any aspect of the actual content that forms. Returning to our completed quantum gravity theory, we have as a given that this completed theory will offer up a wavefunction (or something similar) that gives us the probabilities of a set of possibilities of particles, fields, spacetime etc. and any other unproblematic third person entity. What we're suggesting is a second process that operates on the wavefunction and that this process is equivalent to a spacetime boundary with a filtered set of possibilities occurring in the interior.
The best way, in my opinion, of making sense of these inchoate notions is by appealing to the notion of perspective. We have a perspective (which is physical through and through) acting on a wavefunction (which represents a measure on a set of possibilities) and thereby “filters” a subset of these possibilities. That is, we have in mind a kind of “naturalizing Nietzsche” approach. (Nietzsche is well known for suggesting that perspectivism is a middle ground between absolute and relative, or between objective and subjective.) We have in mind a naturalized perspectivism. Perspectives are natural operators, operating on a naturalistic base which can be conceived as a measure on a set of possibilities (wavefunction).
The perspective has a boundary in spacetime and walls off certain events that occur in the interior of the perspective (qualia). By bringing in perspectives, are we assuming the answer in advance? We don't think so since we claim that a perspective is just a necessary condition for qualia. Also, in developing the theory, the notion of perspective must be mathematically unpacked. That is, the theory must show how boundaries are formed and what kind of operators are involved etc. Is this idea coherent? At present, I don't think so. It is much too vague. However, the important points are:
i) a multiverse that specifies a measure on a “bottom up” set of possibilities - possible values of particle properties, fields, spacetimes etc. and
ii) a set of perspectives that operate “top down” on the multiverse. The interaction of perspectives and the multiverse generates experience. The price of admission is a naturalized perspectivism which we hope is more palatable than the varieties of materialism, idealism, dualism and panpsychism that are already on the table. Tagged with: experience, physics, possibilities, perspectives, supervenience, quantum gravity, naturalized perspectivism Add Comment posted by Anand

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