Conversations with Zombies
By Todd C. Moody
From Journal of Consciousness
Studies, 1 (2), 1994, pp. 196-200.
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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, 1974) 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, 1992) 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 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 philosophy. 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 consciousness[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. Notes
This short article gave rise to a much longer symposium entitled "zombie
earth" in a later issue of this journal. [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, 1978). [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. References
Flanagan, O. (1991), The Science of the Mind ( Jaynes, J. (1976), The
Origin of Consciousness in the Breakdown of the Bicameral Mind ( Kirk, R. (1974), `Sentience and behavior', Mind, 83, p. 60. Nagel, T. (1986), The
View from Nowhere ( Searle, J.R. (1992), The Rediscovery of the Mind ( |
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