Todd C. Moody, Department of Philosophy, St. Joseph's University, 5600 
City Avenue, Philadelphia, PA 19119, USA.

Journal of Consciousness Studies, 1 (2), 1994, pp. 196-200.

Abstract: The problem of `conscious inessentialism' is examined in the 
literature, and an argument is presented that the presence of 
consciousness is indeed marked by a behavioural difference, but that 
this should be looked for at the _cultural_ level of speech communities.

The `zombie problem' is the problem of consciousness, stated in a 
particularly provocative way. Given _any_ functional description of 
cognition, as detailed and complete as one can imagine, it will still 
make sense to suppose that there could be insentient beings that 
exemplify that description. That is, it is possible that there could be 
a behaviourally indiscernible but insentient simulacrum of a human 
cognizer: a zombie. This is so because the best functional description 
can only map inputs onto behaviours by means of computations of some 
sort. That certain computations are associated with consciousness is at 
most a contingent fact about them. The problem is reiterated at the 
level of any possible physical description of cognition as well. In this 
case, the intervening processes between inputs and behaviour will be of 
a causal, rather than formal, sort.[1] Nevertheless, the link between 
those processes and consciousness is still contingent. As long as the 
link between publicly observable states of any sort and consciousness is 
contingent, zombies are a possibility. The zombie problem is a variation 
on the `other minds' problem, but I hope to show that it is not an idle 
variation. It offers, I think, a vivid way of conceptualizing the 
philosophical questions about consciousness. Suppose there is a world 
much like our own, except for one detail: the people of this world are 
insentient. They engage in complex behaviours very similar to ours, 
including speech, but these behaviours are not accompanied by conscious 
experience of any sort. I shall refer to these beings as zombies.[2] 
This scenario, though surprising, is a possibility suggested by a theory 
recently referred to by Owen Flanagan as `conscious inessentialism', 
which is defined as follows:

the dominant philosophical theory of mind, _computational functionalism_ 
was (and still is) committed to the view of _conscious inessentialism_. 
This is the view that for any mental activity M performed in any 
cognitive domain D, even if _we_ do M with conscious accompaniments, M 
can in principle be done without these conscious accompaniments. 
(Flanagan, 1991)

Conscious inessentialism clearly entails that any given behaviour could 
also occur without conscious accompaniments. The only reason why one 
would suppose that certain behaviours do require conscious 
accompaniments is that the behaviours in question appear to require 
mental activity of some sort. Since conscious inessentialism tells us 
that no mental activity requires conscious accompaniments, it follows 
that no overt behaviour requires them either. So if conscious 
inessentialism is true, zombies are possible. Indeed, if conscious 
inessentialism is true, it is quite possible for an entire world of 
zombies to evolve, which is the premise of the current thought 
experiment. It is behaviours, after all, and not subjective states, that 
are subjected to evolutionary selection pressures. If those behaviours 
do not require consciousness, then evolution is indifferent to it. That 
the zombie problem may have significant metaphysical implications is 
concluded by Robert Kirk in a paper on the topic: `it is hard to see how 
any intelligible version of Materialism could be reconciled with the 
logical possibility of Zombies, given that we are sentient'. (Kirk, 

Is conscious inessentialism true? One argument for conscious 
inessentialism was intimated above: the most that we can ever hope to 
establish by empirical means is the regular correlation of observable 
states of some sort with consciousness. Such a correlation warrants only 
a conclusion of a contingent relation. Another source of support for 
conscious inessentialism comes from cognitive psychology. Increasingly, 
scientists are finding that what happens in consciousness is not 
essential for understanding mental functioning. We recognize each other, 
solve problems, use language, and although all these things have 
`conscious accompaniments' it seems that the real work is not done 
consciously at all. In short, cognitive science is drifting towards a 
kind of epiphenomenalism. The artificial intelligence research programme 
is a part of this drift. To quote Flanagan again:

Whereas most skeptics of strong artificial intelligence press worries 
that machines cannot be given consciousness, computational functionalism 
can be read as making this objection irrelevant. Mind does not require 
consciousness. (Flanagan, 1991)

The same point is made by John Searle, commenting on the intelligibility 
of the distinction between conscious and unconscious robots.

as far as the ontology of consciousness is concerned, behavior is simply 
irrelevant. We could have _identical behavior_ in two different systems, 
one of which is conscious and the other totally unconscious. (Searle, 

If conscious inessentialism is true, then it would presumably be 
impossible for us to tell whether visitors from another world are 
zombies. After all, if there is no necessary behavioural difference 
between them and us, as conscious inessentialism requires, there would 
be no identifiable mark of zombiehood. This at least is what appears to 
follow from the thesis. I shall argue that the `mark of zombiehood' will 
be found not at the level of individuals but at the level of speech 

Let us begin by looking at the language of the zombies, and the sorts of 
things they might say with it. Let us suppose that they speak zombie-
English, a language that looks much like our own English language. 
Certain words of zombie-English would have to have meanings somewhat 
different from their English counterparts. For example, the word 
`understand' in English refers not only to what sorts of performances a 
person is capable of, given certain inputs and outputs, but also to a 
particular kind of conscious experience. I use this example because it 
is so familiar from Searle's Chinese Room argument. To understand 
Chinese is more than to be able to produce passable answers to 
questions. There is something it is like to understand Chinese, or 
anything else. Understanding has a phenomenology.

For a zombie, however, it is not like anything to understand Chinese, or 
anything else, because it is not like anything to do anything. So when a 
zombie uses the word `understand' we must understand that he or she is 
not making any reference to any sort of conscious experience. To 
distinguish zombie-English words of this ilk from their English 
counterparts, I shall use the superscript[z]. Thus, we can say that 
zombies understand[z] many of the same things that we understand.

We can imagine being visited by the beings from zombie-Earth. Our 
natural science might look a great deal like theirs, and our mathematics 
would likely be very similar. That is, their beliefs[z] in these domains 
could easily be supposed to be very close to our beliefs. But there 
would also be some interesting differences, especially in the domain of 

Consider, for example, the phenomenon of dreaming. Could there be a 
cognate concept in zombie-English? How might we explain dreaming to 
them? We could say that dreams are things that we experience while 
asleep, but the zombies would not be able to make sense[z] of this. For 
them, the word `experience[z]' can have at most a behavioural meaning. 
Indeed, zombies would understand[z] sleep[z] itself quite differently 
from the way we do. The word `conscious[z]' could only mean responsive 
to the environment.

Still, we can imagine that it happens on the zombie world that upon 
waking[z] from sleep[z], one finds[z] that one has acquired apparent 
memories[z] that are not consistent with the rest of one's beliefs[z] 
and memories[z], and so forth. The zombies might refer to this coming-
to-seem[z]-to-remember[z] as dreaming[z]. But that is not the end of the 
matter, as we shall presently see.

If there are zombie philosophers, they would be able to make no sense[z] 
at all of the other minds problem. They might, of course, be able to 
ponder[z] an `other zombies' problem: how do we know[z] that there are 
not other beings whose experience[z] is accompanied by a quality that we 
cannot fathom[z]? But it is unlikely that this problem would occur to 
them, until they met us. At that point, the zombie philosophers might do 
a great deal of thinking[z] about the things that we try to explain to 
them. They would be especially puzzled[z] by our human philosophical 
literature about dreaming, especially the debate between those who argue 
that dreams are experiences and those who, like Dennett, argue that they 
can be explained as coming-to-seem-to-remember.[3] To the zombie 
philosophers, Dennett's position would be clear enough. What would be 
mysterious is the opposing (and, in fact, more `common sense' to us) 
view, that dreams are experiences. So, even though zombies might 
dream[z], their concept[z] of dreaming[z] would not be philosophically 
problematic in the way that ours is.

Zombie philosophers would be persistently baffled[z] by the fact that we 
talk about `consciousness' as if it were something more than being the 
subject[z] of experiences[z]. What more could it be? Would they be able 
to make sense[z] of the inverted spectrum problem? It is hard to see how 
they could. This is an interesting example, since even those human 
philosophers who argue that it is a pseudo-problem are nevertheless able 
to understand it.

The inverted spectrum problem would not work in zombie philosophy 
because it depends upon a concept of `internal seeing'. This concept is 
found not only in academic (human) philosophy, but also in imaginative 
literature and film. In the `Terminator' science-fiction films, for 
example, we are occasionally given a `robot's-eye view' of the world, in 
which the bottom portion of the screen is filled up with various 
readouts: distance to target, velocity and the like. As human viewers of 
the film this device makes sense to us, because we can conceive of a 
kind of `internal seeing' in which we can look at the readouts while we 
also look at the world. This imaginative device could make no sense[z] 
at all to zombies, because the idea of `internally seen' readouts has no 
zombie analogue or purpose.[4]

Philosophers - human, earthbound philosophers - have argued that the 
other minds problem cannot be solved except by analogy, and that there 
is no empirical content to the notion of a zombie. That is, they argue 
that because there is no behavioural (and therefore observable) `mark of 
zombiehood', it follows that the concept has no real content. But I hope 
that I have shown that while it is true that zombies who grew up in our 
midst might become glib in the use of our language, including our 
philosophical talk about consciousness and dreams, a world of zombies 
could not _originate_ these exact concepts as they are played out in 
philosophical discourse and imaginative idea-play, such as science 
fiction. Their discourse would have gaps in it (from our perspective), 
and concepts from our discourse (philosophical and imaginative) would be 
permanently untranslatable into theirs. This is important, because it 
suggests a qualification to conscious inessentialism. Even though the 
activities of talking about the philosophical dream problem or internal 
seeing do not require consciousness, the _emergence of those concepts in 
a language community_ does. This means that at the level of culture 
there are _necessary behavioural differences_ between zombies and non-
zombies, because those differences are the result of the differences in 
the conceptual vocabularies available to each culture. At the level of 
_culture_, conscious inessentialism is false.

What is most interesting is the fact the zombie scientists would have to 
regard consciousness (not consciousness[z]) as something beyond the 
scope of their science. They would be forced to conclude[z] that 
consciousness is not consciousness[z]. But their science is 
methodologically just like ours. Suppose that human scientists were to 
develop what they took to be the complete scientific explanation of 
consciousness and deliver it to the zombie scientists, saying: `Here is 
the full explanation of human consciousness. We hope it answers your 
questions.' It wouldn't, though. No matter how replete a scientific 
explanation of consciousness we might present to the zombie scientists, 
they would still have no inkling[z] of the explanandum. This is another 
way of stating Nagel's point that the scientific worldview explicitly 
excludes the subjective. (Nagel, 1986, Ch. 2).

That the zombies are different from us is a fact discoverable not by 
natural science but by a kind of hermeneutic analysis of the sorts of 
things that we talk about and what we have to say about them.[5] The 
mere fact that the zombies (as we would later recognize them to be) do 
not philosophize about internal seeing in the way that we do would not 
entail that they are zombies. That we could not explain that problem to 
them, however, would raise suspicions. Further analysis would clarify 
the conceptual gaps. But do these gaps cast a shadow of doubt upon 
materialism, as Robert Kirk claimed? Nagel claims that they do not:

The fact that mental states are not physical states because they can't 
be objectively described in the way that physical states can doesn't 
mean that they must be states of something different. The falsity of 
physicalism does not require nonphysical substances. It requires only 
that things be true of conscious beings that cannot, because of their 
subjective character, be reduced to physical terms. (Nagel, 1986, p. 29)

These facts lead Nagel to a dual aspect theory, although he concedes 
that such a theory is `largely hand waving' (_ibid._, p. 30). That is, 
reality has those aspects that can be encompassed within natural 
scientific theory and those aspects that, in principle, cannot. The 
conscious aspect of reality can neither be reductionistically eliminated 
nor explained by natural science. This means that there are not 
necessarily any discoverable physical differences between zombies and us 
that would explain the phenomenological difference. This counts against 
materialism because these phenomenological differences are perfectly 
real but are not part of the `natural order', as it is materialistically 
construed. They cast a shadow, if you will, into the natural order in 
virtue of our ability to talk about them. Zombies may be able to ape our 
consciousness-talk, but they cannot _originate_ it with any hope of 
getting it right.

My own view is that this radical incompleteness of natural science with 
respect to consciousness entails, at the minimum, an equally radical 
agnosticism about the ontology of minds and persons. It means that we 
are not in a position to insist that materialism is true, and that 
therefore nonmaterialistic hypotheses and research programmes cannot be 
rejected a priori. The appeal of a dual aspect theory is that it avoids 
the difficulties of ontological dualism, but it is indeed mostly hand 
waving. It does not really explain why it should be that the stuff of 
the world has irreducibly distinct categories of properties. As I see 
it, dual aspect theory is largely an attempt to disguise the 
incompleteness of materialism. It is steadfastly materialistic at the 
level of `substance' and quarantines the problems of dualism to the 
level of `properties'. Ontological agnosticism is more candid.

This line of thinking has some interesting corollaries. Zombies are, in 
relation to us, in the same predicament that most of us are in relation 
to those mystics who report back to us their experiences of what is 
sometimes called superconsciousness. We can ape what they say, if we 
want to, but we don't really know what we are talking about. This 
difficulty is sometimes referred to in the mystical literature as 
`ineffability', but the mystics understand each other, just as human 
non-zombies do.[6]

There is a literature on the question as to whether the things that 
mystics say count as evidence for the reality of a transcendent order of 
some sort. Given the absence of an independent way to verify their 
statements this presents grave difficulties. Nevertheless, we can easily 
imagine the parallel case of the zombie philosophers wondering[z] 
whether our consciousness-talk is evidence of something other than mere 
conciousness[z]. We can understand that they might be sceptical[z], even 
though to us there is nothing more real than consciousness.

Consider the possibility that a few zombies might discover a discipline 
that, after considerable practice, turns them into non-zombies, like us. 
It would presumably be very difficult to convince other zombies that 
such a discipline has any point, and it would be quite easy for the 
zombies to dismiss the phenomenon as marginal or pathological. The 
zombie scenario does not prove the `validity' of mystical experience, 
whatever that would mean, but it does entail that such experience cannot 
be dismissed on the grounds of its radical unfamiliarity to the rest of 
us. We might, after all, be zombies.

[1]  The precise difference between causal and formal processes is 
itself a matter of some controversy, which I need not go into here.

[2]  This is of course not what the word `zombie' really means, but this 
usage is now part of the jargon of philosophy of mind.

[3]  Daniel C. Dennett refers to this as the `cassette theory' (Dennett, 

[4]  I am indebted to Jonathan Shear for thinking of this ingenious 
example, and for also pointing out that, to the extent that the 
Terminator is supposed to be a zombie-like automaton, the device makes 
no sense in the movie either.

[5]  This approach, which could be dubbed `speculative hermeneutical 
analysis', is similar to the empirical hermeneutical analysis pioneered 
by Julian Jaynes (1976), whose reading of the _Iliad_ and other early 
texts suggested to him the existence of a pre-conscious `bicameral' 
mind. In both cases, an inferential link is established between the 
nature of mind and kinds of possible language games observed.

[6]  Like mystics, we all have a highly metaphorical phenomenological 
language for describing the variations in our states of consciousness. 
We talk about feeling `fogged in' or `sharp', and we understand each 
other. Their problem is that they must adapt the language of non-mystics 
to their purpose.


Dennett, D.C. (1978), `Are dreams experiences?' in _Brainstorms_ 
(Montgomery, VT: Bradford Books)

Flanagan, O. (1991), _The Science of the Mind_ (Cambridge, MA: MIT 
Press), p. 309.

Jaynes, J. (1976), _The Origin of Consciousness in the Breakdown of the 
Bicameral Mind_ (Boston: Houghton Mifflin Co.).

Kirk, R. (1974), `Sentience and behavior', _Mind_, 83, p. 60.

Nagel, T. (1986), _The View from Nowhere_ (Oxford: Oxford University 

Searle, J.R. (1992), _The Rediscovery of the Mind_ (Cambridge, MA: The 
MIT Press), p. 71.