Identifying the Identity Theory

While I was perusing the new entries over at PhilPapers yesterday I came across Tom Polger‘s forthcoming paper in Philosophical Psychology Are Sensations Still Brain Processes? The paper is very interesting (disclaimer: I have a special interest in this stuff; see for instance The Identity Theory in 2-D) and I thought I would summarize its main points and then say something about where we disagree towards the end.

The first part of the paper Polger identifies eight theses that Smart defended in his celebrated paper. These are,

1. Sensation reports are genuine reports

2. Sensation reports do not refer to anything irreducibly psychical

3. Sensations are “nothing over and above” brain processes

4. Sensations are identical to brain processes

5. The identity theory is a metaphysical theory, not a semantic proposal or an
empirical hypothesis

6. Metaphysical theories of the nature of the mind do not make competing
empirical predictions; so they should be evaluated by their theoretical virtues,
e.g., simplicity and parsimony

7. For any thing or kind x, there are “logically” necessary conditions for being a thing of that kind.

8. Sensation expressions are topic-neutral.

The first claim is simply an endorsement of realism about phenomenal consciousness. Claims 2-4 spell out commitments to physicaism and the identity theory. Claims 5 and 6 spell out Smart’s distinctive views about the identity theory. Claim 7  basically asserts that we can know a priori what pains are essentially. Claim 8 amounts to the idea that concepts like ‘pain’ etc do not entail a commitment to any kind of ontology all by themselves.

Polger goes on to argue that of these every one but 7 should be accepted by contemporary identity theorists. Claim 6 should be accepted but not interpreted too narrowly. The identity theory should be accepted for broadly ‘inference to the best explanation’ reasons. Parsimony and simplicity play a role in that inference but there are other things that also play a role; As Polger says, “There are also what Jaegwon Kim has called explanatory and causal arguments for the identity theory”. The reason that 7 should be rejected according to Polger is the kind of resources that Kripkean arguments give to the identity theorist. In place of 7 above Polger suggests 7*

7*. A Posteriori. The identity of sensations and brain processes is a posteriori

7* is then an updated version of Smart’s claim that mind/brain identities are to be construed as ordinary scientific identities. We now have a post-Kripkean understanding of these kinds of identities and the contemporary identity theory should reflect that.

In the second part of the paper Polger goes on to formulate a master argument against the identity theory that he thinks subsumes all arguments against it and then responds to the various particular objections. The master argument goes as follows;

(P1) If the identity theory is true, then there is a necessary one-to-one relation between sensations and brain processes.15 (necessity of identity)

(P2) If VARIATION then there is not a necessary one-to-one relation between sensations and brain processes. (definition of VARIATION)


(P4) There is not a necessary one-to-one relation between sensations and brain processes. (P2, P3)

(C2) The identity theory is false. (P1, P4)

The particular objections that we find spell out varieties of variation claims: actual, nomological, metaphysical, logical. Polger identifies one major figure and style of objection this way. So, Putnam’s worries about octopi and Fred’s pain at 6:00 v.s. Fred’s pain at 6:15 count as actual variation while Fodor’s worries count as nomological, Kripke’s modal argument is metaphysical, and Chalmer’s zombie argument is logical. All of these arguments are united by trying to show that there is or can be variation.

Polger has a lot of interesting things to say in response to each of these objections.  Against actual variation he argues that even if we grant, as we might not, that we find the very same psychological properties across species on Earth (that is to say, even if an octopus can feel the very same kind of sensation that I do when I experience pain) there is still very little reason to think that psychological properties are multiply realizable in a way that is threatening to the identity theory. Sure there may be differences between species but that is no reason to rule out similarities a priori! Some people cite neural plasticity as a possible source of trouble. To this Polger replies, “evidence from plasticity is compatible with the neurobiological variations being variants within a more general kind that is also neurobiological.” Lacking any reason to believe in actual variation we also have no reason to believe in nomological variation, what about metaphysical variation? Here Polger endorses type-b physicalism and argues that Kripke’s argument is question begging. If the mind-brain identities are true then they are necessarily true. This leads Polger to the last kind of variation which he calls logical variation. It is here that we find Polger’s discussion of Chalmer’s zombie argument. His main complaint is that the argument rests on an assumption about the nature of reduction that the type-b physicalist will reject.

In the final section of the paper Polger introduces two further claims which he thinks should be endorsed by contemporary identity theorists.

9. Variability. Sensation processes are multiply constituted.

10. Strong Physicalism. Physicalism is necessarily true; all worlds are physicalist worlds.

In defense of accepting 9 Polger argues as follows,

accepting that there is…variability in the world is a far cry from accepting that it is the kind of variability that would be problematic for identity theories. Identity theories claim that sensations are brain processes, but they do not take any stand on the nature of brain processes. In particular, the identity theorist need not suppose that the world is organized into homogeneous columns of organization so that there is a one-to-one relation between sensations and microphysical processes. The identity theorist identifies sensations with brain processes, not with molecular or subatomic processes that occur inside brains.

I have always been sympathetic to this kind of argument and have seen some of my own work as generally supporting it. But what about 10? Why ought we accept that? The basic reason is to avoid the following reductio of the identity theory;

C1. Sensations are identical to brain processes in all possible worlds. (identity theory)

C2. Physicalism is contingent; there are some non-physicalist worlds containing non-physical sensations. (contingent physicalism)

C3. There are some worlds in which sensations are not identical to brain processes. (from C2)

C4. The identity theory is false.

Polger’s answer to this argument is to give up C2 thereby blocking C3. This may seem dramatic and I take 10, together with 7*, to entail that there are strong necessities in Dave Chalmers’ sense, “but”, says Polger, “so it goes. Just as there are necessary a posteriori truths, there are necessary a posteriori falsehoods.”

But it is just at this point that the difference between the kind of identity theory that Polger has and one that is in 2-D. Once we start thinking in 2 dimensional semantics we can see an equivocation in the redictio. C1 should be modified as C1*

C1* The secondary intension of ‘Sensations are brain processes’ is necessary; the primary intension of ‘sensations are brain processes’ is contingent (identity theory in 2-D)

Once we do that we do not have the worry about the reductio. Adopting C1* is tantamount to a compromise between 7 and 7*. In effect we agree that there is an a priori knowable description or reference fixer and an a posteriori identified physical state. Given that we know independently that identities like this are 2-necessary in Dave Chalmers’ sense we can conclude that those identities are necessary in spite of possible worlds where the a priori knowable description picks out a non-physical property.

Applied Mathematics and Scrutability

Also via Leiter’s blog I was perusing the Philosopher’s Annual list of the ten best papers of 2008. The paper on Mill is very interesting and I have heard a lot about belief and alief lately but what really caught my attention is Penelope Maddy’s How Applied Mathematics Became Pure.

The whole paper is really very interesting and I would highly recommend that you read the whole thing but I want to quickly discuss one of the morals that she draws from the story she tells. She says,

This story has morals, it seems to me, about how mathematics functions both in application and in its pure pursuit. One clear moral for our understanding of mathematics in application is that we are not in fact uncovering the underlying mathematical structures realized in the world; rather, we are constructing abstract mathematical models and trying our best to make true assertions about the ways in which they do and do not correspond to the physical facts. There are rare cases where this correspondence is something like isomorphism – we have touched on elementary arithmetic and the simple combinatorics of beginning statistical mechanics, and there are probably others, like the use of finite group theory to describe simple symmetries – but most of the time, the correspondence is something more complex, and all too often, it is something we simply do not yet understand: we do not know the small-scale structure of space-time or the physical structures that underlie quantum mechanics. And even this leaves out the additional approximations and accommodations required to move from the initial mathematical model to actual predictions.

I wonder if this is right if it causes problems for the kinds of scrutability claims that David Chalmers wants to defend, and which for the most part I am highly sympathetic to (of course where we differ is over whether we need to include phenomenal truths in the base truths or not…I think probably not since they can be derived just as easily as other ordinary macroscopic truths).

The problem, it seems to me, is that if this is right (i.e. if at the limit we do not end up with a unified mathematical model of the world but rather patchwork models that apply only in various respects) then which mathematical model we apply or assumption we make will crucially depend on empirical knowledge (for instance knowing that the equations for a harmonic oscillator  are a good model of a molecule’s vibration only in the region of the minimum (see page 35)). Am I missing an easy response?

I’ll have to think about it later because now I’m off to Jared Blank’s cogsci talk

Zombies and Impossible Worlds

Via Leiter’s blog I happened to be looking at the list of recent SEP entries. I read this entry on impossible worlds that got me thinking.

The response to the zombie argument that I have been developing over the last couple of year appeals to the distinction between prima facie and ideal conceivability. Something is prima facie conceivable, roughly, if there is no obvious contradiction in the imagined scenario. Something is ideally conceivable if, roughly, there is no contradiction in the imagined scenario even upon ideal reflection. I have tried to argue that zombies are merely prima facie conceivable and may not turn out to be ideally conceivable (another way of putting it that is roughly equivalent is that zombies are epistemically possible but not metaphysically possible) since there are equally plausible parity arguments (zoombies and shombies). As a corollary of this line of defense I have argued that what people like Dave actually succeed in imagining when they *think* they imagine the zombie world is really just a world that is very similar to the actual world. Just as a point of clarification I have always meant this to be a different claim than the Russellian response that the zombie world may have different ‘inscrutable’ fundamental physical properties. What I mean is that since we do not yet know all of the facts about the brain, physics, or theories of consciousness, we may be inadvertently failing to include some crucial physical law, property, or theory of consciousness. So it is very easy, I claim, to imagine a world that is physical in roughly the same sense that ours is but where there is no consciousness. For instance, if the higher-order thought theory of consciousness is right then the ‘zombie’ world is really just a world like ours that lacks higher-order thoughts.

Now people like Dave often claim that they can conceive that we add this feature and yet still it is intuitive that those creature could lack consciousness. If this is really the case and the higher-order theory is true then Dave has imagined an impossible world. But it seems to me that we can at this point admit that the traditional zombie world is conceivable and go on to argue for a restriction on the second premise of zombie argument, which to remind us, is the claim that if zombie are conceivable then they are possible. This premise becomes possibly false since it may be the case that zombies are conceivable but not metaphysically possible, where this means that they inhabit an impossible world.

One response to this line of thought might be that the use of ‘conceivability’ here isn’t the same as that employed by the zombie argument. As used by Dave ‘conceivable’ means roughly imaginable without contradiction but in these impossible worlds we conceive of a world with a contradiction (by stipulation it contains a contradiction). But, of course, the point here is that one may not notice or be in a position to spot the contradiction, which is exactly one of the reasons for postulating impossible worlds (or in this case impossible scenarios in Dave’s sense). If one takes this line, as I am inclined to do myself, then the issue reduces to the original one of the difference between prima facie conceivability and ideal conceivability. But if one has a more generic version of conceivability one can argue that zombies are conceivable and impossible in way that seems different from the usual type-b line…

Explaining Consciousness & Its Consequences

Yesterday I presented Explaining Consciousness and its Consequences at the CUNY Cognitive Science Speaker Series which was a lot of fun and a very fruitful discussion. I have a narrated powerpoint rehearsal of the talk and those that are interested can look at that at the end of this post but here I want to discuss some of the things that came up in the discussion yesterday.

The core of the puzzle that I am pressing lies in asking why it is that conscious thoughts are not like anything for the creature that enjoys them. My basic claim is that if one started with the theory of phenomenal consciousness and qualitative character and came to understand and accept it but one hadn’t yet thought about conscious thoughts one would expect that the theory would produce cognitive phenomenology. Granted it wouldn’t be like the phenomenology of our sensations –seeing blue consciously is very different from consciously thinking that there is something blue in front of one– but why is it so different that in one case there is nothing that it is like whatsoever while in the other case there is something that it is like for the creature? The only difference between the contents of HOTs about qualitative states and HOTs about intentional states is that one employs concepts of mental qualities whereas the other employs concepts about thoughts and their intentional contents yet in one case conscious phenomenology –which is to say that there is something that it is like for the creature to have those conscious mental states– in all its glory is produced while in the other case nothing happens. As far as the creature is concerned it is a zombie when its has conscious thoughts. But what could account for this very dramatic difference? It looks like we haven’t really explained what phenomenal consciousness is, all we have done is re-locate the problem to the content of the higher-order thought. This is because no answer can be given to my question except “that how phenomenal concepts work” and so we have admitted that they are special.

Now one thing that came up in the discussion, by David Pereplyotchik, was what I meant by ‘special’ in the above. David P. suggested that qualitative properties may be distinctive without being special. I agree that they are distinctive and that is the reason that thinking that p and seeing blue are different. We move from distinctive to special when we deny that conscious thought have a phenomenology because we can’t explain why they don’t.

One detail that came out was that the way I formulated the HOTs and their contents was misleading. Instead of “I think I see blue*” the HOT has the content “I am in a blue* state”

At some point David said that when he had a conscious thought what it was like for him was like feeling one was about to say the sentence which would express the thought. So when one thinks that there is something blue in front of one what it is like for that creature is like feeling that they were about to say “there is something blue in front of me”. When I said ‘aha, so there is something that it is like for you to have a conscious mental state’ he responded “what does that mean?” This challenge to my use of the phrase “what it’s like for one” was a main theme of the discussion. A lot of the time I ask whether or not there is something that it is like for one to have a conscious thought  and if not why not but David objected that the phrase is multiply ambiguous and is used to confuse the issue more than anything else. One way this came out was in his challenging me to explain what was at stake. What difference is made if we say that there is something that it is like for one to have a conscious thought and what is lost if we deny it? I responded that it is obvious what the reference of the phrase ‘what it is like for one’ is. It is the thing that would be missing in the zombie world. David responded that the zombie world was impossible, which I agree with at the end of a long theoretical journey but we can still intuitively make sense of the zombie world even if only seemingly. That is even if it is the case that zombie are inconceivable we still know what it would mean for there to be zombies and that still helps us zone in on what the explanatory problem is. I take it that the whole point of the ambitious higher-order theory is that it tries to explain how this property, the one we single out via the phrase ‘what it is like for one’ and the zombie and mary cases, could be a perfectly respectful natural property. So what is at stake is whether or not I really am like a zombie when I have a conscious thought and what that means for the higher-order thought theory. If we cannot account for the difference between intentional conscious states and qualitative conscious states then we have not explained anything.

David’s main response to my argument seemed to be to appeal to the different ways in which the concepts that figure in our HOTs are acquired. In the case of the qualitative states we acquire the concepts that figure in our HOTs roughly by noticing that our sensations misrepresent things in the world. So, if I mistakenly see some surface as red and then come to find out that it isn’t red but is, say, under a red light and is really white, this will cause me to have a thought to the effect that the sensation is inaccurate and this requires that I have the concept of the mental quality that the state has. In the case of intentional states the story is different. We are to imagine that there is a creature that has concepts for intentional states but only applies them on the basis of third person behavior. This creature will have higher-order thoughts but they will be mediated by inference and will not seem subjectively unmediated. Eventually this creature will get to the point where it can apply these concepts to itself automatically at which point it will have conscious thoughts. This difference is offered as a way of saying what is different about the concepts that figure in HOTs about qualitative states and those that figure in HOTs about intentional states. It amounts to an elaboration of David Pereplyotchik’s suggestion early on that the qualitative properties are distinctive without being mysterious. They are distinctive in the way that concepts are acquired. But as before how can this be an answer to the question I pose? I agree that there is this difference for the sake of argument. What seems to me to follow from this is what I said before; namely that the phenomenology of thought and the phenomenology of sensations is not the same…but this should be obvious already. So, the claim is not that having a conscious thought should be like seeing blue for me or feel like a conscious pain for me only that it should be like something for me. Basically then, my response is that this will make a difference in what it is like for the creature but doesn’t explain such a drastic difference as absence of something that it is like for one in one case.

Another way I like to put the argument is in terms of mental appearances. David Rosenthal often says that what it is like for one is a matter of mental appearances at which point I argue that the HOT is what determines the mental appearances and so in the case of thinking that p it should appear to me as though I am thinking that p. In response to this David said that while it is the case that phenomenology is a matter of mental appearances it might not be the case that all mental appearances are phenomenological. At this point I have the same response as before…viz. what reason do we have to think that there are these two kinds of appearances? It looks like on is just inserting this into the theory by fiat to solve an unexpected problem. There is no theoretical machinery which explains why we have this disparity. When we ask why applying starred concepts results in appearance of qualitative phenomenology the application of intentional concepts does not so result in intentional phenomenology when we ask why? We are simply told that this is the way phenomenology works. It is as mysterious as ever.

At the close of the talk I touched briefly on Ned Block’s recent paper “The Higher-Order Theory is Defunct” which raises a new objection to the higher-order theory based on the consequences of explaining consciousness as outlined here. The problem that Ned sees is that when one has an empty HOT one has an episode of phenomenal consciousness that is real but that is not the result of a higher-order thought. David’s response seems to be to fall back on his denial that there are ever actually cases of empty higher-order thoughts. I brought up Anton’s syndrome and David responded that in Anton’s syndrome we don’t have any evidence that they actually have visual phenomenology. They don’t want to admit that they are blind but when we ask them to tell us what they see they can’t. If there are never empty higher-order thoughts then Block’s problem goes away.

My response to this problem is to identify the property of p-consciousness with the higher-order thought while still identifying the conscious mental states as the target of the HOT but at that point we adjourned to Brendan’s for some beer and further discussion.

During the discussion at Brendan’s we talked a little bit about my suggestion that we develop a homomorphism theory of teh mental attitudes. David and Myrto wanted to know how many similarities there were between sensory hommorphisms and the mental attitudes. In the sensory case we build up the quality space by presenting pairs of stimuli and noting what kind of discriminations the creature can do. What we end up doing is constructing the quality space from these kinds of discriminatory abilities. So, what kind of discriminations would happen in the mental attitude case? I suggested that maybe we could present pairs of sentences and ask subjects whether they expressed the same thought or different thoughts. Dan wanted to know what the dimensions of the quality space for mental attitudes would be. I suggested that one would be degree conviction, so that whether one doubts something or believes something firmly or just barely will be one dimension of difference but I have yet to think of any others. This has always been a project I hope to get to at some point…right now its just a pretty picture in my head…

Ok well I feel like I have been writing this all day so I am going to stop…

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