The Rise and Fall of Zombie Philosophy
November 28, 2013
Joe Polanik

By 'zombie philosophy' I mean any philosophy of (human) consciousness which assumes or from which follows the conclusion that humans satisfy the traditional criteria used to define the philosopher's zombie:

  1. Physiologically human
  2. Without qualia

By 'zombie philosopher' I refer to (human) philosophers who advocate a zombie philosophy as just defined.

In what follows I discuss the specific form of zombie philosophy known as 'type-Z(ombie) materialism' as well as the philosophy of Daniel Dennett whose position is an instance of zombie philosophy as I've defined that term; although, it is not an instance of type-Z materialism.

Before proceeding however, I'll pause for an important qualification. this is not about whether a given philosopher uses the word 'quale(s)/qualia'. the word is considered controversial by some philosophers; and, for whatever reason, they simply don't use it. for example, someone might say that the term is hopelessly muddled; and, that it would be a waste of time to try to clarify its meaning.

That doesn't matter, as long as there was some other term that could be used. for some philosophers, there isn't. for example, Daniel Dennett does more than reject the use of the term 'quale'. He rejects the use of alternate terms and the existence of anything to which such terms are used to refer. in Consciousness Explained, in the chapter entitled "Qualia Disqualified", he writes:

Philosophers have adopted various names for the things in the beholder (or properties of the beholder) that have been supposed to provide a safe home for the colors and the rest of the properties that have been banished from the 'external' world by the triumphs of physics: 'raw feels', 'sensa', 'phenomenal qualities', 'intrinsic properties of conscious experiences', 'the qualitative content of mental states', and, of course, 'qualia', the term I will use. There are subtle differences in how these terms have been defined, but I'm going to ride roughshod over them. In the previous chapter I seemed to be denying that there are any such properties, and for once what seems so is so. I am denying that there are any such properties. But (here comes that theme again) I agree wholeheartedly that there seem to be qualia. [p. 372]

Clearly, Dennett rejects not only the word 'quale' and various alternatives terms; he rejects the existence of that to which such terms are typically used to refer. It is on that basis that I classify Dennett as a zombie philosopher.

Daniel Dennett and the Origin of Type-Z Materialism

Dennett would no doubt deny that he is a zombie philosopher. his view is that zombies are 'inconceivably preposterous'. Nevertheless, further along in "Qualia Disqualified" [p. 406] he states:

There is another way to address the possibility of zombies, and in some regards I think it is more satisfying. Are zombies possible? They're not just possible, they're actual. We're all zombies. 6

Dennett effectively retracts his speculation almost as fast as he makes it, footnote 6 reads "It would be an act of desperate intellectual dishonesty to quote this assertion out of context".

What are we to make of this? it makes no sense that I can see for a philosopher to say "Zombies are conceivable, possible and actual; and, we are they! --- but don't quote me on that." In any event, others have developed Dennett's suggestion into a strongly paradoxical instance of zombie philosophy: type-Z (for zombie) materialism.

The term 'type-Z materialism' is analogous to the terms 'type-A materialism' and 'type-B materialism' in that they are distinguishable by their responses to Chalmers' zombie argument against materialism.

In its original form, the zombie or conceivability argument, has three premises and a conclusion. letting P represent the conjunction of all physical facts true of our universe; and, letting Q represent some arbitrary phenomenal fact (eg. 'I am conscious' or 'I am experiencing pain' or whatever); then, the zombie argument is

  1. P & -Q is conceivable
  2. if P & -Q is conceivable, P & -Q is metaphysically possible
  3. if P & -Q is metaphysically possible, materialism is false
  4. (therefore) materialism is false

According to Chamers, [The Conscious Mind p. 166],

Chalmers does not discuss the possibility that a philosopher might concede both [1] and [2], the conceivability and possibility of zombies, and deny only [3]. Beisecker explores this option in "Zombies, Phenomenal Concepts and the Paradox of Phenomenal Judgement" [Journal of Consciousness Studies. 17(3-4):28-46. 2010.]

Beisecker writes:

This paper explores the viability of rejecting a largely unchallenged third premise of the conceivability argument against materialism. Fittingly labeled 'type-Z' (for zombie), this reply essentially grants to the zombie lover, not just the *possibility* of zombies, but also their actuality. We turn out to be the very creatures Chalmers has taken such great pains to conceive and more conventional materialists have tried to wipe off the face of the planet. So consciousness (at least for us) is a wholly material affair. What is conceivable but non-actual are not zombies, but rather 'angelic' beings possessing an acquaintance with supermaterial phenomenal states. [p. 28]

Beisecker acknowledges that type-Z materialism has not been widely considered; and, he mentions Dennett's "We're all zombies" remark as a kind of anticipation of type-Z materialism; but, he is careful to note that Dennett ends up with a type-A materialist position.

Crucial for understanding the rhetorical strategy of the type-Z materialist and the flaws of that strategy is Beisecker's clarification of 'supermaterial'.

'Super-materialist' is my preferred term for those who follow Chalmers and accept that the zombie argument (or the knowledge argument) demonstrates that there must be more under heaven and earth than is countenanced by (mundane) materialism, for the moniker nicely captures an ambivalence in how the position is understood. To their materialist opponents, supermaterialism advocates us to accept the existence of spooky, supernaturalistic, non-material features of the world, while supermaterialists themselves think they are simply urging us to acknowledge an underlying, instrinsic facet of our material existence, which has heretofore eluded systematic scientific investigation. [p. 30 fn 1]

Surely, this characterization of the dispute between zombie philsophers and their opponents, while seriously overblown, is not completely false.

Beisecker is quite right to suggest that Chalmers and other opponents of materialism advocate accepting the existence of something whose existence the materialist must deny; and, that such a position constitutes dualism; but, he is wrong to suggest that any and every such position counts as substance dualism (the obvious connotation of 'supernatural and non-material').

What Chalmers and the earlier Jackson urge that we accept is qualia; but, I do not read them as saying that a typical quale, for instance, the color of an afterimage, is itself an immaterial, supernatural being.

Is there a less inflammatory reading of anti-materialism, one that preserves Beisecker core claim that the anti-materialistic position is dualistic without exaggerating the degree of dualism necessary to constitute anti-materialism? If so, the next task would be to identity the claim that constitutes a minimally dualistic anti-materialism.

Constructing a Minimally Dualistic Anti-Materialism

In this effort, we can benefit from considering Dennett's presentation to the most 2013 Online Conference on Consciousness. In this video, Dennett guides the viewer to induce an afterimage of an American flag; and, focuses the experiencer's attention on one particular red stripe (marked with a cross in the original complementary-color image of a flag).

Dennett admits that one can refer to the red stripe in experience; that nothing in the brain is identical to that red stripe; and, that dualism follows unless the materialist has an adequate defensive response.

Does substance dualism follow from the fact that nothing in the brain is identical to the red stripe in experience? I don't think so; and, I don't read Dennett to be saying that. Instead I take Dennett to be saying that dualism of some sort follows unless the materialist has an adequate defensive response.

Once one admits that nothing in the brain is identical to the red stripe in experience, how does one defend materialism?

Dennett's strategy for defending materialism is to deny the existence of the red stripe in experience after inducing a flag afterimage; and, he offers the would be defender of materialism some ways to support the claim of non-existence. Before evaluating the effectiveness of any of these suggested tactics, we should clarify the burden that the defender of materialism must discharge.

Given that nothing in the brain is identical to the red stripe in experience; and, assuming (as seems reasonable) that no material object outside the brain is identical to the red stripe in experience, it follows that the red stripe in experience --- if it exists at all --- does not exist as a material object.

However, from the proposition that the red stripe in experience does not exist as a material object it does not follow that it does not exist in any sense whatsoever.

Would Dennett's defense of materialism survive the admission that the red stripe in experience exists in some sense despite not existing as a material object?

I suspect not. If Dennett argues that the red stripe in experience exists in some sense despite not existing as a material object, he would be in the position that John Searle finds himself in, a position recognizing two modes of existence, one for publically accessible, material objects and one for color quales and other privately accessible, experienceable phenomena that exist only while being experienced. Searle's position on this point is arguably dualistic, the position Dennett is defending against; so, adopting something like Searle's position to defend materialism would be an act of desperation.

Consequently, I take it that a Dennettian defender of materialism must either assume or conclude that the red stripe in experience after inducing a flag afterimage does not exist in any sense whatsoever. If Dennett fails to discharge that burden, he would have a defense gap.

Evaluating Dennett's Defense of Materialism

How successful is Dennett's defense of materialism?

A careful evaluation of Dennett's attempt to make sense of the claim that the red stripe in experience does not exist in any sense whatsoever reveals some serious problems in Dennett's defense of materialism.

Problem 1: Theory of Referencing

On some theories of referencing, one can't refer to that which does not exist in any sense whatsoever. Defenders of materialism might try to adopt a non-standard theory of referencing; but, such an ad hoc move would likely evoke intense opposition; particularly, from the analytic perspective. In any case, Dennett does not offer such a theory of referencing.

Problem 2: Argument for the Non-Existence of the Red Stripe

Dennett advises that the defender of materialism assert that the red stripe in experience is "... an intentional object which doesn't have to exist."

Suppose Dennett's premise is universal, perhaps something like [P1].

[P1] No intentional object which does not exist as a material object exists in any other sense.

If so; then, from the claim that the red stripe in experience is an intentional object; and, the claim that the red stripe in experience does not exist as a material object, Dennett could conclude that it does not exist in any other sense. However, introducing an unsupported assumption weakens the defense of materialism.

On the other hand, suppose Dennett's premise is not universal, perhaps something like [P2].

[P2] Some intentional objects which do not exist as material objects do not exist in any other sense.

Now Dennett would have the problem of showing that the red stripe in experience is among the intentional objects which do not exist as material objects and which don't exist in any other sense. He makes no attempt to do so.

Problem 3: Suspension of Standard Logic

If the red stripe in experience does not exist in any sense whatsoever, how can it be an intentional object? How can nothing at all can 'be' an intentional object? this has not been explained.

The logical flaw here is that attributing a predicate presupposes the existence of the subject of predication. so attributing the predicate 'intentional object' to the red stripe in experience assumes the existence of the red stripe; thereby contradicting Dennett's claim that the red stripe in experience does not exist in any sense whatsoever.

If we tried to represent Dennett's position in logical symbols what would we get?

where a = the red stripe in my afterimage experience
O = is an intentional object
∃ represents the existential quantifier

We might try

(∃x)(Ox & (x = a) & -∃a)

But, that makes no sense at all.


It seems clear that Dennett faces serious problems attempting to defend materialism by denying the existence of qualia, the move that defines a zombie philosophy.

So, why 'go zombie' in the first place?

Clearly, Dennett wants to avoid what he calls "the shortest, sweetest and actually in the end the most convincing argument for dualism" that he knows:

If A is a red stripe and nothing in the brain is a red stripe, then nothing in the brain is identical to A which has to be somewhere else! Dualism follows.

[ at about 12:45 into the video]

While I agree with Dennett that some sort of dualism follows from the short and sweet argument, I would deny that substance dualism follows.

It may be that Dennett and other defenders of materialism fear that admitting the existence of qualia is just the first step on a slippery slope that will inevitably result in unpalatable conclusions. if so, denying the existence of that which distinguishes humans from zombies seems like a high price for insurance against the risk that someone someday might find a way to deduce substance dualism from the existence of afterimages.

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