In the following I look at two fronts on which you might battle Chalmers’ arguments against physicalism about consciousness. The first is from Polgar’s recent paper (discussed recently by Richard Brown) in which Polgar briefly critique’s Chalmers’ implicit theory of reduction. The second is the more common strategy of attacking him for assuming he can conceive of zombies in the first place. I argue that the second strategy is better, though they are not mutually exclusive.
A weaker front: Supervenience and reduction
In his paper Are Sensations Still Brain Processes? Polgar says the following about Chalmers’ zombie argument against physicalism:
[T]he a posteriori identity theorist quite reasonably rejects the problematic notion of “logical” conditions and the positivist demand for a special kind of “reduction” of which there are no non-trivial examples and that has long since been rejected by philosophers of science. The burden is on the objector to show independently that the identity theorist, or any physicalist, should require such reductions. And no such positive argument has been given.
Recall Chalmers’ argument: if physicalism is true, fixing the values of the physical facts logically fixes the value of the facts about consciousness. This is equivalent to the supervenience claim that different consciousness-facts entail different physical-facts. Note when I say ‘physical facts’ I mean facts about things in physics, brains, stuff your run-of-the-mill naturalist likes to use as a supervenience base.
It seems, then, that the inchoate view of reduction Polgar refers to is the ‘logical fixation’ of one set of facts by another. In practice, Chalmers says we need to determine if physical-facts fix consciousness-facts by using a conceivability test. Can we conceive of C-facts shifting while the P-facts stay the same? If so, then physicalism fails.
I’m not sure what is positivisic about Chalmers’ view, or what in his view has long been rejected by philosophers of science. Intuitively, he seems right. When we fix the chemical facts we have fixed the higher-level facts about this cup of water (e.g., is it in liquid or solid phase). When the facts about molecules in this gas are fixed, the facts about its temperature, pressure, etc. come along ‘for free’ so to speak. This seems reasonable, basically a restatement of the claim that consciousness supervenes on the physical.
Based on such considerations, Polgar’s claims seem a weak front on which to attack Chalmers’ argument, especially when communicating with people that don’t know any philosophy. Perhaps a philosopher in the house can clarify or defend what Polgar was saying.
More promising: tempering the conceivability arguments
Another argument against Chalmers accepts his argument strategy, but attacks the high credence he gives his intuitions about how C-facts and P-facts logically relate to one another. How do facts about brains relate to facts about conscious experiences? Our understanding of both sets of facts is so undeveloped that Chalmers’ confidence seems premature.
By analogy, many people don’t understand how facts about energy relate to facts about mass, they can’t conceive of any possible logical route from one to the other. Most people’s understanding of energy is about as clear as our present characterization of phenomenal facts, so this seems an apt analogy. While facts about energy don’t supervene on facts about mass, that shouldn’t change the conceptual point.
The analogy people usually bring up against Chalmers is vitalism. Vitalists couldn’t conceive of how physico-chemical facts related to certain biological facts, and used this to infer that the physico-chemical picture of life was incomplete. The vitalist Driesch stated his argument strategy quite nicely when he claimed (in ‘Science and Philosophy of the Organism’ (1908), p105):
[S]omething new and elemental must always be introduced whenever what is known of other elemental facts is proved to be unable to explain the facts in a new field of investigation.
Driesch’s argument for vitalism was an application of that general inference rule. For instance, he argues (ibid, 142):
No kind of causality based upon the constellations of single physical and chemical acts can account for organic individual development; this development is not to be explained by any hypothesis about configuration of physical and chemical agents. Therefore there must be something else which is to be regarded as the sufficient reason of individual form-production…
This is a good example of a conceivability argument hitting the rocks.
Chalmers would likely argue that the analogy fails because in Dreisch’s argument the target facts were “easy” facts about development, not “hard” facts about consciousness. This would be to miss the point that we need to exercise extreme caution when consulting our conceptual intuitions about what follows from what. That we now believe one group of facts is easy to reach from the other is clearly a contingent fact.What guarantee can Chalmers offer that he isn’t falling victim to a similar failure of imagination, lured by his contingent limited understanding of facts about brains and facts about consciousness?
I don’t really buy Polgar’s argument, but am willing to be set straight. The more obvious and central problem with Chalmers’ arguments is his willingness to take too seriously how he presently conceives of the relationship between two targets that themselves are not particularly well defined. Indeed, we could argue that our present understanding of the two targets is even less well delineated than Driesch’s two targets were when he was writing.