To: Katie H.
From: Geoffrey Klempner
Subject: The 'hard' problem of consciousness
Date: 21 February 2008 12:33

Dear Katie,

Thank you for your email of 10 February, with your second essay for the Associate program, entitled, 'The nature of consciousness and the explanatory gap.'

This essay has the potential to be a very useful survey of the current state of debate over the 'hard' problem of consciousness.

My main criticism is that it did read a bit like too much of a mere survey. A survey is fully acceptable in, say, physics, where you are collating a wide range of results and presenting a summary of the different positions for the benefit of a researcher who is looking for a fruitful topic to investigate.

The difficulty with doing this in philosophy is that the statement of the 'position' that a philosopher holds is not fully separable from argument about the nature of the problem. You do succeed in doing this to some extent, although not as much as I would have liked.

There is definitely something very interesting to say here, about different conceptions of the 'explanatory gap', its 'hardness' or 'softness', whether the gap is fundamentally ontological or merely epistemological. However, these possible views about the explanatory gap need to be related more closely to the different arguments for the existence of a gap in the first place.

Consider, for example, Chalmers' notorious zombie argument. First, I would question whether Chalmers is an interactionist. If there is no physical basis on which I can be distinguished from my zombie double, then any causation from the mental to the physical must be undetectable, having no observable consequences which differ in the case of my zombie double where causation is from the physical to the physical. This looks like epiphenomenalism to me.

The question, however, is, What is the zombie argument an argument *for*? We have two candidates:

(1) The view argued in different ways by Nagel, Searle and McGinn that physical science is incapable of grasping the nature of consciousness -- a view which is consistent with holding that mental events ultimately have a physical nature, but we just can't grasp it, either because physics as a method of inquiry is restricted to the objective view (Nagel) or because our present science is simply too primitive (Searle) or because of a fundamental restriction in the kinds of concepts that the human mind is able to form (McGinn).

Or,

(2) The view that the universe contains, in addition to physical entities, a second kind of entity which is not necessarily a soul as Descartes believed but is essentially non-physical, which one might call a 'Cartesian mental event' or CME in recognition of the fact that *I* know, without any possible room for doubt, when a CME is occurring while it occurs. I *know* what the colour 'blue' looks like to me at this moment, what a 'tickle' feels like and so on. You and I can agree in the 'public meaning' of these *words* but only the subject who is experiencing the CME can be aware of what the word refers to, at the time when the word is used. The definition of CME looks very much like the definition of a 'quale'.

Although Chalmers writes as if he is advocating option (1) it is difficult to read the zombie argument in any way which does not entail an argument for the existence of CMEs, in other words (2). How do I *know* that there could be a zombie physically indistinguishable from me? Only because I am aware of *this* event of consciousness which accompanies the word 'blue' as I remark on the blueness of the sky today, or the word 'tickle' as I implore you to stop tickling me.

The zombie argument is, indeed, highly paradoxical for reasons which you must be only too well aware. As I write my article defending epiphenomenalism and citing the zombie thought experiment as my main argument, my zombie double (on twin earth) is doing exactly the same thing!

The main argument, of course against CMEs is Wittgenstein's private language argument which Dennett repeatedly cites as the final, knock-down refutation of any attempt to introduce qualia.

My personal interest would therefore focus more on conceptions of a gap which are fundamentally epistemological rather than ontological. Dennett, for example, mounts a strong defence of the view that consciousness can, in principle, be 'explained'? What, if anything, has Dennett missed? What evidence is there for the existence of a fundamental failing in the very nature of physical explanation which discredits it from explaining consciousness, or in the nature of the human brain or human concepts which prevents us from grasping the nature of consciousness?

So far as my recommendations for changes go, I am not asking you to necessarily incorporate the points I have made. What I would like you to do, however, is to make the essay look a bit less like a survey. One way to do this would be by philosophically describing the problem *first* and then, gradually, introducing the various philosophical positions as the need arises rather than start by giving a long list of all the views that have been held.

Also, you are entitled to take a view. Which arguments do you find persuasive, which less so? What are the prospects, in your view, for a resolution of this debate? or is debate destined to go on for ever, without reaching a conclusion?

All the best,

Geoffrey