Here I Go Again!

In a few hours I will be on my way to Tucson for the big consciousness shin-dig! But first I have office hours and a full day of teaching…ah well. I may be slow in responding to comments (though I will respond to Josh in person in the form of a twenty minute drum solo entitled ‘Pain Asymbolics are in Pain, it’s just not Painful’ 🙂

The Inconcievability of Zombies

There has been a surprising amount of talk about zombies recently around the blogosphere. Here I thought the zombie issue was settled back in the ’90’s; but I suppose that’s what I get for forgetting that there aren’t any solved problems in philosophy, and it is in the nature of zombies to come back from the dead so I suppose I shouldn’t be all that surprised.

At any rate this zombie flare-up was brought about by Richard Chappell’s argument against physicalism. It starts by claiming that there is a possible world where there are creatures exactly like us in every physical way but who lack conscious experience. They scream when stabbed and ohh and ah over Matisse but ‘all is dark inside’; they are merely going through the motions since they do not have any conscious mental experiences. Since this world is conceivable it is metaphysically possible and since this world is metaphysically possible that means that physicalism about consciousness is false. This is, of course, not new with Chappell; this is the argument developed by David Chalmers. Chappell then presses JAckson and Chalmers’ argument that the popular Kripkean response fails to meet the zombie challenge. He argues that the zombie world is conceivable and whatever we decide about the way we want to use our words (i.e. whether we decide to apply our word ‘consciousness’ to the zombies), the metaphysical possibility of that world is enough to refute physicalism.

I have been arguing that Chappell’s argument fails to address the most plausible physicalist response to the zombie argument (and that his defense of modal rationalism itself adopts a version of the Kripkean strategy). This is to deny that the zombie world is actually conceivable. Sure, it seems to Chappell that he is imagining a world where there are physical duplicates of me (or you) and no consciousness but he is really imagining a world that LOOKS a lot like there are physical duplicates of me (or you) which lack consciousness. This is what I have been calling the Kripkean response because it is exactly the strategy that Kripke adopts in Naming and Necessity. It seemed to people that they were imagining a world where water wasn’t H2O (or where Aristotle wasn’t Aristotle) but they are really imagining a world where there is stuff that LOOKS like water does to us which isn’t H2O (or a world where there is a person who LOOKS like Aristotle (or satisfies most or all of the descriptions that Aristotle satisfies in the actual world) who isn’t Aristotle). Why should we think this is really what is going on? There are many reasons:

1. Do Conscious Mental States Cause Behavior?

 If the answer to this question is yes then it is obvious that zombies are inconceivable. The zombie world is a world physically just like ours but which lacks conscious experience. Conscious experience act as causes of behavior, so a world that lack them would not be one where things went on as usual. It would be a world that was missing a bunch of causes and so, if just like ours, would have creatures that looked like us but would not act just like us. This is basically the argument that John Perry developed in his “Knowledge, Possibility, and Consciousness”.

2. Do We Have Epistemic Access to Our Conscious Mental Experience?

 If the answer to this question is yes then the zombie world is inconceivable. This is the argument developed by Robert Kirk in his book “Zombies and Consciousness” (and the one being talked about over at Overcoming Bias). Here is a quick summary of the argument (from my review of the book for phil. psych.)

The anti-zombie argument can be stated rather easily. According to the ‘zombist’ there can be a creature that is a molecule-for-molecule-duplicate of me and yet lacks phenomenal consciousness. At the same time they want to hold that we have ‘epistemic access’ to our phenomenal consciousness. These two claims are not consistent with each other. To see why, imagine a zombie world that is identical to ours except in respect of phenomenal consciousness. Since that world is just like ours we can assume that it is causally closed under the physical. Now, continues Kirk, it should be possible to add to that world whatever it is that the zombist thinks will transform it into a world that does have phenomenal consciousness. But since whatever we added would have to be nonphysical, since their world is identical to ours (excepting consciousness), and so could not interact causally with the physical world (which is closed under the physical), it follows that we could not know anything about these ‘e-qualia’. Therefore, we could not have ‘epistemic access’ to them.

To make this vivid he offers what he calls the ‘sole-pictures’ argument. Again, consider our zombie world. Let’s add whatever it is that the zombist thinks will transform it into a world like ours. Now let’s imagine that by a “strange shift in the natural laws” of the zombie world the visual processes that in me cause e-qualia instead cause

sequences of constantly changing pictures to appear on the soles of [the zombie twin’s] feet. The changing colored patterns on his soles are isomorphic to those neural process in the same way as my e-qualia are isomorphic…to similar process in my brain. (p. 45)

Is there any reason to think that the zombies will have any access to these sole-pictures? Kirk’s answer is ‘NO!’ If not then zombies are not conceivable. The zombist commits what he calls the ‘jacket fallacy’: They treat qualia as something that can be stripped off a world without changing anything in the way that I can remove a jacket and remain the same. In the second half of the book Kirk tries to construct a theory of perceptual-phenomenal consciousness that does not commit the jacket fallacy.

This argument is convincing to me, and others. Has anyone responded to it?

3. Do qualitative properties (partially) Constitute our Phenomenal Beliefs?

If the answer to this question is yes then zombies are inconceivable. This is the option that Chappell and Chalmers opt for. They argue that qualitative properties are epiphenomenal in that they do not causally interact with the physical states of my brain but since the partly constitute the phenomenal beliefs I have (or in other words, my beliefs about what phenomenal states I am in). My zombie twin will believe that he sees red when I do but whereas I have a belief whose content is partly constituted by the epiphenomenal non-physical property ‘redness’ (or whatever), my zombie twin’s phenomenal beliefs lacks this property entirely and so we have very different beliefs even though we are physically identical. This seems conceivable and so it may seem that this response avoids the kind of physicalist response I am suggesting. But this is too quick.

The reason it is too quick is because of the discovery of pain asymbolia. Pain asymbolia is a rare condition where people report that they are in pain, and can even tell you what kind of pain it is (burning, pinching, stabbing, etc) yet they do not feel it as painful. The distinctive painfulness of the pain is absent. Presumably then these patients have an our world equivalent of the kind of beliefs that Chappell and Chalmers take the zombies to have. But far from acting in the same ways that we do when we have the same beliefs + qualitative painfulness these pain asymbolics laugh and smile at the pains. So the world that Chappell is imagining is not physically just like ours. If it were then the zombies would not behave in all the same ways that we do.

All of these discoveries come from a posteriori investigation. Even on Chappell’s modal rationalism these all turn out to be a posteriori discoveries because they depend on which world is actual. A purely rational being would not a priori whether the answers to 1-3 were ‘yes’ or ‘no’ until looking at the world. This is the Kripkean strategy. Chappell hasn’t argued against it and it doesn’t fall prey to the arguments he does develop.

HOT Implies PAM: Why all Higher-Order Theories of Consciousness are Committed to a Phenomenal Aspect for All Mental States, Even Beliefs

Here is the virtual presentation for my upcomming Tucson presentation (you may have to press play if it doesn’t automatically start after opening). It is also available on the side bar with the other virtual presentations. It is a decendent of the presentation I gave at the ASSC, but instead of sketching my view of the propositional attitudes as consisting of a qualitative mental attitude held towards some intentional content, I consider several objections to the argument raised by Rocco Gennaro, Josh Weisberg, and David Rosenthal. Comments are as always very welcome.

The Higher-Order Response to the Zombie Argument

I have been having a very interesting discussion with Richard Chappell about his argument against physicalism and for modal rationalism which got me to thinking. If the higher-order theory is right, any version of it, then there is a very nice response to the zombie argument to be made. The zombie argument depends on there being a possible world that is exactly like the actual world except that the people and animals that inhabit this world do not have any conscious experience. As I have been arguing with Richard, one promising response to this argument is to claim that we are not really imagining a world that is exactly like ours except without consciousness we are really imagining a world which looks a lot like this one and which has no consciousness.

But what kind of world would this be? There would have to be people that looked liked us and behaved like us. They would say and do all the things we would do but the would not have consciousness. There would be nothing that it was like for them when they cried or were in “pain”. If one thinks about this from the higher-order view point this is a description of a world where there are no higher-order representations. That is, this is a world where there are only first-order states and no accompanying higher-order states. But how could that world be exactly the same as this one? In this one the presence of the first-order states leads to the arrival of higher-order representations. Something must be different about this zombie world.

Chappell on the A Priori

The a priori seems to be on the rise of late, especially with defenders like Richard Chappell championing the cause. According to Chappell an ideallly rational being would have access to all the metaphysical possibilites. Given that we can ideally (or coherently)  conceive something we can infer that the thing in question is metaphysically possible. This is, of course, the basis for the zombie argument against materialism. Since we can coherently concieve of a zombie world (a world where there are beings like us in every physical way except that they lack conscious experience) that shows that consciousness cannot be a physical property.

The standard (Kripkean) objection to this line of argument is to try to distinguish between metaphysical and epistemic possibility. Some things that are epistemically possible (i.e. seem coherently conceivable) turn out to be impossible (a classic example is to point out that before you learn that the square root of 1,987,690.000 is 1409.855 (rounded up to the nearest thousandth) it is concievable that it be other than 1409.855 but once we find out what it is it is impossible for it to be otherwise. According to the materialist one of these things is the zombie world. While it seems that we can coherently concieve of such a world, we are actually missing some contradiction, or physical difference between our world and the zombie world and so it is not actually (ideally/coherently) concievable. 

Chappell objects to this line of argument for (at least) two reasons. The first has to do with the theoretical extravagance of the materialist’s claim that the identity between (say) H2O and water is necessary. It posits an unexplained strong necessity, wheras the modal rationalist (the one who thinks that it is a metaphysical possibility that water could be other than H2O, not just an epistemic possibility) doesn’t have to posit something like this. All that she needs to posit is a single uniform space of possibilities that we describe in various ways. The materialist has to posit a space of epistemically possible worlds and a seperate space of metaphysically possible worlds. Parsimony and simplicity seem to favore that modal rationalist here.

The second is an attack on the claim that calling something a rigid designator settles the dispute. As Chappell says,

Perhaps our term ‘consciousness’ is, like ‘water’, a rigid designator. But who cares about the words? Twin Earth still contains watery stuff, even if we refuse to call it ‘water’, and the Zombie World still lacks phenomenal stuff (qualia), even if we stipulate that our term ‘consciousness’ refers to some neurophysical property (and so is guaranteed to exist in this physically identical world).

Yes it will, IF we have settled the issue in favor of Chapell’s view and we then think that we are genuinely concieving of a real metaphysical possibility. If there is a question as to whether these kinds of possibility are distinct then Chapell has done nothing more than beg the question.

This is evidenced when he says,

Kripke himself noticed something along these lines. While we can imagine a world where watery stuff isn’t truly water, it’s incoherent to imagine a world where “painy” stuff isn’t truly pain. To feel painful is to be painful.

Pointing out that Kripke begs the same queston as you are beging is not a way to absolve yourself of beging the question. There is a legitimate case to made that being in pain and feeling pain are in fact two seperate things. The evidence for this comes, not from a priori reflection on the nature of pain, but from evidence from cognitive science.

 But suppose that you are not moved by this evidence and you still maintain that a priori analysis reveals that the zombie world is metaphysically (not just epistemically) possible. Is this a coherent position? One objection that immediately pops up is that on this view it seems that we can concieve of various possible worlds that result in contradiction. So, I seem to be able to concieve that God necessarily exists and that God necessarily doesn’t exist (or that numbers do and don’t necessarily exist). Since the claim that conceiveability entails possibility entails that God (or numbers) both necessarily exists and doesn’t exist only one of those possibilities can be a real metaphysical possibility; the other must be an epistemic possibility.

Chappell is of course aware of this objection and tries to deal with it in the post linked to above. Here is what he says,

I agree with Chalmers that the most attractive response for the modal rationalist here is to hold on to their strong position, and instead deny the… conceivability intuitions found, for example,…above. It isn’t at all clear that a necessary being, or a shrunken modal space, is coherently conceivable in the appropriate sense. The modal rationalist will want to hold that their position is not just true, but a priori. They would then expect opposing views to be refutable a priori, and hence not feature in any a priori coherent scenario. Of course, it would beg the question to merely assert: “the thesis is true and hence has no successful counterexamples”. But that is not what’s going on here. Rather, I hope to show that the modal rationalist can explicate their commitments in a way which makes clear exactly why, on their view, the meta-modal cases in question are not taken to be genuinely conceivable. If successful, this should suffice to undermine the charge of internal inconsistency or self-refutation.

The problem with this line of argument is that it commits the very ‘fallacy’ that Chappell accuses the Kripkeans of making. The strategy that he is here proposing is that of trying to show that there is some possible state of affairs that seems conceivable but which, on reflection, is not in fact metaphysically possible (i.e. that there are possibilities that (seem)concievable but are not metaphysically possible). But if there are possibilities that (seem) concievable but not metaphysically possible then we need an independent argument that the zombie world is not one of these worlds. No such argument has been given. Rather what Chappell does is to assume that it is in fact coherently concievable; but this cannot be assumed if there are any possibilities which (seem) concievable and are not metaphysically possible. Chappell’s own view commits him to there being such possibilites, so by his own view the modal argument against materialism is suspect.