Dawn of the Dead: Are Zombies Possible?

Inspired by a recent post on Philosophy, et cetera, I want to talk a little about zombies and what they imply for a materialist theory of the mind.

When I say “zombie,” I don’t mean the shambling, flesh-eating undead of horror films. This thought experiment is about philosophical zombies, which are a different beast altogether. The philosophers’ zombie is a hypothetical creature which, to all outward appearances, is indistinguishable from an ordinary human. The difference is that they lack phenomenal consciousness – they lack qualia.

Qualia are the subjective sensory perceptions of our inner mental life. We see colors: the redness of red, the greenness of green. We hear tones, sharp or high-pitched or dull or low. We taste flavors, salty or bitter or sweet. We feel emotions like joy, anger, or sadness. Zombies, by contrast, have none of these experiences. They are not truly conscious of anything, any more than a stone is conscious, but they act exactly as if they were. A zombie can duck a thrown baseball or write a restaurant review. Point a gun at one and it will flinch and act as if it were afraid.

What does such a bizarre idea have to do with atheism? The answer is that some prominent philosophers claim that zombies are a conclusive disproof of any strictly naturalistic theory of how the mind functions. The train of argument usually goes that zombies are not a metaphysically impossible notion; it involves no self-contradiction to imagine their existing. If they are not self-contradictory, then they are possible. If they are possible, then we could hypothetically build one – a sophisticated robot, let’s say. Such a being would act with rationality and apparent intelligence, yet lack consciousness. But if it’s possible to be an intelligent, rational being without consciousness, the question is, why aren’t we zombies? What makes us different from the robot? The answer, they say, is that there must be a supernatural component to the mind, in other words, a soul. This supernatural component is what gives us our consciousness, our qualia, whereas a being lacking that component could never truly be conscious no matter how much mental processing power it might have.

The problem with zombies, as with many philosophical notions, is that they do not truly prove a point but simply play on people’s differing intuitions about what is possible. No obvious self-contradiction arises when we imagine a zombie, I grant. It is logically possible for such a thing to exist. But that does not mean that zombies are possible in our world, under the laws of physics that hold sway here. Our ability to imagine them is no disproof of this. We, fallible humans, are not cognizant of all the laws of physics, much less their almost infinitely complex hierarchy of ramifications. An intelligence like Laplace’s demon, with perfect knowledge of the universe, might well see some consequence of physical principles which we overlook, and which renders zombies impossible in our world.

Consider a similar example. Just as dualist philosophers claim they can imagine creating a zombie, I claim I can imagine creating a perpetual motion machine. I couldn’t tell you exactly how to build it, just as no one can say exactly how to build a zombie, but I can readily imagine some marvelous machine – blinking lights, coils of wire conducting electric arcs, spinning flywheels, a big brass switch – that, once it’s powered up, begins producing free energy out of nowhere. No self-contradiction arises when I imagine this. But does that mean we can actually build one? Have I just disproved the laws of thermodynamics without getting out of my armchair?

Obviously not. Though we may think we can imagine a working perpetual motion machine, reality is bound to disappoint. So far, every attempt to build one has ended in utter failure, stymied by some physical principle they failed to take into account. The laws of our universe, it appears, interlock in such a way as to perfectly rule out the possibility of perpetual motion machines. There is no loophole where an inventor, however clever, can slip through. It only seems possible because our imaginations do not take into account the critical details that any practical attempt cannot avoid.

The dualists, I believe, are in the same boat. They may think they can imagine zombies, but that doesn’t mean they’re actually possible. Indeed, I suspect the opposite is more likely true: any creature complex enough to behave with all the creativity and adaptability of a human being would have to have consciousness and qualia, or something very much like them.

After all, how could a zombie dodge a thrown baseball, unless its eyes (or cameras) conveyed images of nearby objects; unless those images were in some way converted into an internal model of the world; and unless that model contained some data stream or symbol which represented a small, round, rapidly approaching object? How could a zombie write a restaurant review unless its chemical sensors were linked to a sophisticated mapping of what readings correspond to what flavors and the many subtle ways in which various combinations could interact with each other? How could a zombie convincingly simulate fear unless it had a wide-ranging ability to keep track of events in the external world and infer which ones could pose a threat to its continued existence?

It is not at all obvious to me that a being with such a sophisticated repertoire of memory, understanding and perception could fail to be conscious. In fact, I strongly suspect the opposite: any being with this capability would have to be conscious, given the physical laws that hold in our world. Consciousness is not an optional add-on, but an inevitable product of a certain degree of cognitive sophistication. In particular, I believe the ability to explicitly represent one’s own self in one’s mental catalog of objects, and to introspect one’s own internal information processing – which, again, a zombie can do – is a vital building block of true consciousness as humans possess it, if it is not consciousness itself.

The dualists assume that an intelligent being could fail to possess qualia, and therefore conclude that intelligence and consciousness are separable. But this claim is an example of the fallacy of circular argument. If you assert that it’s possible to hold everything else about the world constant, but subtract consciousness, then you’re not arguing for dualism, you’re assuming dualism! The conclusion which you wish to reach is already contained in the starting assumptions you feed into your argument. Whether consciousness is an inevitable outcome of the working-out of physical laws inside intelligent brains, or whether it’s an unnecessary epiphenomenal accompaniment, is the very thing at issue. I argue that, contrary to some people’s intuition, consciousness and intelligence are in fact not separable. I can’t prove it; but neither can the dualists prove that they are.

The only remaining question, which I admit is a vexing one, is: why qualia? Why does consciousness have any subjective character at all? The way in which our minds represent characteristics of the external world as ineffable interior perceptions does seem strange, and not like most other phenomena we encounter. It does indeed seem difficult to imagine that any science, however advanced, could explain precisely how such subjective experiences arise from the collisions of atoms inside the brain.

But our inability to imagine it, at this point in time, is no proof that it’s impossible. The existence of life was also once considered to be an impenetrable mystery, inexplicable except by postulating a supernatural “vital force”. Yet life has since been shown to have an explanation comprehensible in terms of physical laws. (Overcoming Bias writes about “encapsulating the mystery as a substance” – an apt description of the situation.) I see no reason to believe that qualia will prove to be any different. Though they may seem to be a fundamentally different kind of thing, that’s just an artifact of our present ignorance. Most likely, qualia arise from the physical laws of the cosmos no less than any other natural phenomenon. We don’t understand precisely how – and maybe the mysterians are right, and we never will – but still, that is no proof that it is impossible.

About Adam Lee

Adam Lee is an atheist writer and speaker living in New York City. His new novel, Broken Ring, is available in paperback and e-book. Read his full bio, or follow him on Twitter.

  • http://passionateatheist.blogspot.com NoAstronomer

    Given the criteria you’ve stated for creating a Zombie, I don’t see that it’s possible to prove that all the other people you meet are *not* Zombies.

  • http://www.philosophyetc.net Richard

    If they are not self-contradictory, then they are possible. If they are possible, then we could hypothetically build one – a sophisticated robot, let’s say.

    Quick correction: some prominent philosophers think that the logical possibility of zombies refutes physicalism (even though zombies are of course nomologically impossible, and so could not be built in our world).

  • Wedge

    Have you read Heinlein’s short story “All You Zombies”? Not the same philosophical question, exactly, but addresses NoAstronomer’s comment. And it’s one of his great ones.

  • mikespeir

    “It is not at all obvious to me that a being with such a sophisticated repertoire of memory, understanding and perception could fail to be conscious.”

    I would tend to agree.

    But I wonder how much of this problem is actually definitional. It’s something like saying, “Reason is that mental exercise that humans do.” You’ve just defined reason as uniquely human, although there are apes that can do things that otherwise would have to be seen as products of reason.

    Likewise, isn’t “zombie” just a way of defining a distinction that doesn’t necessarily exist in reality? To me, if it looks, walks, and quacks like a duck, the burden of proof is on those who insist it’s not a duck.

  • Polly

    I lean toward the other end, that we are only deluding ourselves into thinking we are conscious. Much of our neural processing proceeds without our awareness, without our “feeling” it. Systems in our brain can function quite well and perform complex tasks without our controlling or even being aware of them.
    There are no “awareness” neurons in the brain so far as scientists can tell. And much of what we take to be under our control is actually registered in areas of the brain PRIOR to our awareness of them. There’s a fraction of a second delay between an action being “decided upon” by the brain, and our awareness of it.
    What I’ve seen so far tends to make me think we are interpreting brain signals as if they were the result of some “mind’s” decisions.
    You could come back at me and say, well, you’re experiencing things right now, who is it that’s experiencing the thoughts? True. But, how often am I really thinking about thinking? And isn’t that really what self-awareness is, anyway? Most of the time I’m processing the world around me like any computer would take inputs.
    To me, “qualia” seem less like conscious experiences than simply automatic memory association of the context that you first got an input, RED for example. Maybe it was a fire engine with sirens wailing and you got excited. Now, your reflexive response is to get a little rise (increase in heart rate, more adrenaline, etc) when you see bright red.
    The seemingly wide pallette of emotions strikes me as a mere interpretation of the rush of fight-or-flight chemicals in our bloodstream. Phyisically, I can’t tell the difference between being (happily) excited, scared, or angry. The physical response is always the same. Maybe that’s why some people enjoy horror movies (like Dawn of the Dead) and some people seem to enjoy getting angry. (I do)

    I do agree with you that whatever consciousness is, or seems to be, it is inseparable from our big brains being capable of memory and sophisticated information processing. I think we can and will build a computer that mimics those processes and it will be every bit as “conscious” as we are. It’s only our organicism that makes us unable to imagine that a silicon chip can be like us.

  • http://www.currion.net Paul C

    I think that this is one of your rare misses, Ebon. A perpetual motion machine is ruled out by the laws of physics; a zombie absolutely is not. Your baseball-dodging zombie is a case in point – we can already manufacture a machine that dodges baseballs in exactly the way you describe, but that machine won’t be conscious. The point is that processing of sensory data alone is not sufficient to claim to demonstrate consciousness – and writing restaurant reviews is merely a more complicated task than dodging baseballs.

    We wouldn’t know if somebody was a zombie or not – we could never prove or disprove it. I know I’m not a zombie, but I have no way of knowing whether you are or not. I can’t even prove that I’m not a zombie – and I could go further and say that I can’t even prove that I’m not a zombie to myself. NoAstronomer is absolutely right, and everybody should read this if they haven’t already, to understand the true horror of our zombie planet.

    Daniel Dennett makes an appearance, too.

  • DamienSansBlog

    It might help for someone to define “consciousness”, or to explain what exactly it has to do with qualia. A protozoan (or protist, or whatever they’re calling them these days) clearly has “subjective sensory perceptions”. Is it conscious?

  • Entomologista

    The best evidence that dualism, qualia, a soul, or whatever is bunk is that a brain injury can radically alter your personality. Most of philosophy is sheer nonsense anyway.

  • Entomologista

    Ok, Paul C. We can go around assuming that everybody is a zombie, we live in the Matrix, and so on. How do we know what we know?! How do I know I exist?! This is exactly why philosophy is such a waste of time. We can’t answer these questions, and they’re not even particularly interesting questions. On the other hand, the scientific method shows that things work a certain way in the environment we inhabit – because we can use it to predict outcomes. That’s really useful. It’s certainly far more useful that sitting around tearing our hair out over whether or not we’re zombies.

  • David D.G.

    I couldn’t tell you exactly how to build it, just as no one can say exactly how to build a zombie, but I can readily imagine some marvelous machine – blinking lights, coils of wire conducting electric arcs, spinning flywheels, a big brass switch – that, once it’s powered up, begins producing free energy out of nowhere. No self-contradiction arises when I imagine this. But does that mean we can actually build one? Have I just disproved the laws of thermodynamics without getting out of my armchair? Obviously not.”

    Well, no wonder. The switch has to be made of a carbon-tungsten-iridium alloy.

    ~David D.G.

  • http://uncrediblehallq.blogspot.com/ The Uncredible Hallq

    I want to amplify Richard’s point–this is not only how some philosophers think, but it’s actually the standard way of setting up the zombie argument. The idea is that if it’s possible *given different laws of nature* that people physically identical to us might not be conscious, then consciousness must be something above and beyond the physical.

    I’d repharase your point about playing on intuitions about what is possible. If we trust our intuitions, we’re fine. But why trust our intuitions about these possibilities, unless we’re confident we know how things actually are? The argument seems to let our beliefs about how things actually are be disguised as a subtle philosophical argument.

  • http://gretachristina.typepad.com/ Greta Christina

    Yup.

    Supporting the point you made, Ebon, is the fact that software designers and AI experts have had a devil of a time replicating many basic functions of the human brain, such as language. We can say, “Oh, sure, of course you could make a zombie or a robot that would act just like a person” — but in fact, at the moment we can do no such thing. We’re not even close. And I agree that, if we were able to create a creature or a robot that acted as if it had consciousness, it’s very probable that it would have consciousness.

    But maybe I’ve just seen Bladerunner too many times…

  • Polly

    @Paul C:
    Thanks for that link! Reductio ad hilarium.
    That would make a great short film. They should call it, “Dawn of the Dualists.”

  • http://gretachristina.typepad.com/ Greta Christina

    A couple of quick replies to other comments:

    I lean toward the other end, that we are only deluding ourselves into thinking we are conscious…

    This “deluded” trope comes up from time to time in the atheosphere, and I want to address it. Why is “created by humans” or “a product of the human brain and mind” the same as a delusion? The idea that meaning is something we create for ourselves instead of something given to us by God doesn’t make it a delusion; and the idea that consciousness is a product of our brain instead of a metaphysical substance doesn’t make it a delusion either, any more than emotions or thoughts are delusions.

    It might help for someone to define “consciousness”

    It sure would. Alas, if I understand the current state of neuropsychology, I don’t think we’re anywhere near understanding what consciousness it. It seems to be one of the great, unanswered, “we’re working on it” scientific questions of our age.

    I read a wonderful quote about this from Patricia Churchland, a philosopher who promotes the idea that philosophers need to work with scientists — especially neuroscientists — if they want their philosophies to reflect reality. She had this to say about consciousness:

    “Suppose you’re a medieval physicist wondering about the burning of wood,” Pat likes to say in her classes. “You’re Albertus Magnus, let’s say. One night, a Martian comes down and whispers, ‘Hey, Albertus, the burning of wood is really rapid oxidation!’ What could he do? He knows no structural chemistry, he doesn’t know what oxygen is, he doesn’t know what an element is — he couldn’t make any sense of it. And if some fine night that same omniscient Martian came down and said, ‘Hey, Pat, consciousness is really blesjeakahgjfdl!’ I would be similarly confused, because neuroscience is just not far enough along.”

  • Polly

    @GC,

    and the idea that consciousness is a product of our brain instead of a metaphysical substance doesn’t make it a delusion either, any more than emotions or thoughts are delusions.

    Quite frankly I could change my mind tomorrow given new information. I don’t know. Which is why I said I lean that way. I still think life is pretty darn meaningful and I don’t disparage that at all. I am not one of those “nihilist” atheists. I’m a happy one! :)

    It’s not just because it’s a product of our brain. Pain is a product of our brain, but I wouldn’t argue that it’s a delusion. I think our conception about what consciousness is and “how much of it” we’ve got (probably very little IMO), is a delusion.

    Likewise for emotions, which is what I was trying to convey. The same physiological responses get interpreted in different ways in accordance with (from my very own experience) what we expect to feel about some event.
    Drunks typically become jolly or angry depending, in part, on what they expect alcohol to do to their mood. I’m always tempted to laugh out loud at funerals, asian women have a tendency to laugh when nervous.
    I would say that emotions are “real” but they are not what we think they are. They aren’t even all that distinct from one another. One set of responses covers a whole range of emotions, while another set covers the opposite feelings.

    All we feel is change in blood flow, the rest is context-sensitive memory access.

  • steve bowen

    I tend to agree with ebon that any machine or zombie that was sophisticated enough to replicate human behavior convincingly would be conscious. It could be that it is an emergent property that comes with complexity and is simply not within our current technology to produce in a computer. The fact that we can create a robot that will “dodge a baseball” just means we can mimic one aspect of human behaviour, not that we can create a perfect zombie.

  • http://blog.atheology.com Rastaban

    I rarely disagree with anything you write, but in this case I think you’re off base. I agree that the Zombie argument doesn’t help theists at all, but not for the reasons you provide.

    Instead, I would argue that not only is Zombie-ism possible in our world, but that it’s existence is almost certain. We have scientific evidence for it in primates (chimps and humans) in the phenomenon of blindsight, for example.

    In the broader sense, we are all “zombies” when we consider some aspects of brain activity and “conscious” when we consider others. Furthermore, it seems pretty evident that the brain makes “decisions” (& makes them completely outside of our consciousness) about what experiences it will present to us as qualia at any particular moment, as well as how intense those experiences should be. Thus we may be aware of the feeling of clothes against our skin when we first dress, yet later not feel our clothing (until we direct our attention to it again). I take this as an example of the brain turning off (or turning down) the particular qualia of feeling something against the skin. The same goes with other qualia like sound and emotions – the brain turns them on or off, strengthening or weakening them, all the time, sometimes in response to other qualia (like our thoughts) and sometimes not.

    You wrote “Most likely, qualia arise from the physical laws of the cosmos no less than any other natural phenomenon.” Instead I’d say the evidence is that qualia is not an automatic consequence of physical laws at all, but entirely a product of specific brain physiology.

    To take one example, when the brain constructs color experiences, it doesn’t blindly follow wavelength but first actively determines how it will construct the image (ie, whether an area will be represented in shadow) before determining what color qualia to produce. This is why the colors we experience do not have a one-to-one correspondence with the wavelengths of light which strike the retina. The visual cortex produces color and other visual elements based on maximizing their usefulness to the organism; vision is not a consequence of something inherent in the nature of photons, but is rather a neurological construction.

    Zombies do not help the theist at all. As you point out, their argument boils down to: “if it’s possible to be an intelligent, rational being without consciousness, the question is, why aren’t we zombies?” The answer is that obviously evolution took a different path from pure zombie-ism. Sensations turned out to be useful things for organisms to have (all qualia, it seems to me, are forms of sensations). Subjective sensations — from colors to feelings to thoughts — allow organisms a complex method of assigning values to their various needs and options, and in turn provide an intricate and useful way to make decisions in complex environments. Yeah, we could have evolved differently, but we didn’t.

  • Brad

    I read this post and when I saw it was about philosophical zombies, I began to smile. Then the argument came up that it is not technologically possible to construct such a p-zombie. I don’t see that as a serious argument against the principle that the question raises. Certainly we aren’t really going to confine a cat to a box and then set its life dependence on radioactive material and a Geiger counter. But that doesn’t remove the philosophical question, “How can you be alive and dead at the same time?”

    “It is not at all obvious to me that a being with such a sophisticated repertoire of memory, understanding and perception could fail to be conscious.”

    Memory, understanding, and perception (in their cognitive forms) can all be emulated by a computer. In fact, in “Blockbuster,” you said

    “The ability of analysis is not a sufficient condition for consciousness, but it is clearly a necessary one.”

    Consciousness, however, does not seem as if it’s possible to code using abstract symbols or physical cells. How do you tell a program to feel its surroundings and internal states? We have robots that can have light pass through lenses, causing certain types of information about the light to be stored, and then functionally use that information. But does that at all involve the qualia of “redness”? Quickly, could you tell me out of personal experience about the wavelength or frequency of the light corresponding to red? That is not what you experience when you “see” red. Sure, your brain will have neural information about it, but if it weren’t for modern science, you wouldn’t have any idea whatsoever that that was happening. With a robot, there is no holistic self-observer; it is just pieces of logic working together. The brain is likewise a mass of circuitry, but then whence cometh this “I”? This lack of apparent connection between consciousness and functioning intelligence is what makes dualism seem self-evident to many people. A series of dominoes falling seems to us animated, yes, but not itself capable of what we believe is true thought or feeling.

    The point I’m trying to make is that the reasons for suspecting dualism are legitimate. Obviously, there’s no way for us to tell if our friends are p-zombies or that they can in theory be constructed. But the better question is “How can subjective experience rise out of physical processes when they appear so different”? The more foundational questions would inquire as to what these things really are and how they are exactly different, which to many dualists looks like a simple question to answer with “direct knowledge” or “phenomenological validation/revelation.”

    Seems supernatural, eh? Well, I know atheists (like myself) aren’t all very good fans of non-naturalistic models of the universe, but that doesn’t mean it’s impossible to concede the nontriviality of the “hard problem”. I haven’t yet heard an explanation that has sat well with me. If consciousness is a cognitive illusion, then what is there being tricked? Like I said, I don’t have the answer, but I haven’t seen one here or anywhere else for that matter.

  • http://www.bellatorus.com Petrucio

    Very well and nice, but you say that we need a very complex machine to do some things, and probably consciousness to go with it. Let’s see the list of examples:

    1. Duck to avoid a baseball
    2. Taste food, see colors (hear tones? – that’s mine)
    3. Show fear

    All very complex behavior indeed, but all easily performed by several other complex species.

    You frequently point that we are the only conscious species when you try to make a point – as if this was obvious -, yet some other point you make leaves us to assume that the answer to that question is far from obvious.

    I’ve asked about this to you twice already, and I’ve never seen you address that. How’s that cognitive dissonance kicking on that?

    PS: Sorry if this comment seems a little aggressive; is isn’t. I’m really curious about your opinion on this, and I agree with almost everything else you write.

  • Chris

    Indeed, I suspect the opposite is more likely true: any creature complex enough to behave with all the creativity and adaptability of a human being would have to have consciousness and qualia, or something very much like them.

    I take a different position: I don’t believe qualia exist at all. I’ve never seen redness; what I have seen is a variety of objects, of different shapes and sizes, in different positions and lighting conditions, which produced interactions with my retinas that were similar in a way that (I know from experience) English speakers term “red”. When I see an object I haven’t seen before, if it produces retina signals that are similar in that way, I call it red; if not, not. I could be fooled by strange lighting or filters or something like that, though. My brain doesn’t know any more about color than the signal it gets from my retinas.

    Reifying the category (of perceptions of red objects) and overlooking the elements is essentialism – trying to have a forest first, and put the trees in later. Individual perceptions exist, the category is an arbitrary line drawn around some set of them. (Obviously the zombie can’t write a restaurant review without perceptions – which I’ll define briefly as the ability to have some part of your internal state model, more or less accurately, some set of facts about the external world. By this definition a *camera* has perceptions, so it’s a pretty low bar to get over.)

    My father is red-green colorblind; in the absence of prosthetics the interaction between red light and his retinas is the same as the interaction between green light and his retinas. So if he grew up in isolation, he’d put them in the *same* mental category, not different ones. Actually, he probably doesn’t, because he’s aware of the existence of other people who can see a difference, even if he can’t. This implies a difference between the way he perceives redgreen objects, and the way he thinks about them. But as a small child he used to draw pictures with red grass, because he couldn’t tell the red crayon from the green crayon until he could read the label. The redgreen crayon looked the same as the redgreen grass was supposed to look.

    If you imagine someone red-green colorblind who really *did* grow up in isolation (or a society of other dichromats), and didn’t contact trichromats until adulthood, what would such a person/society make of the fact that the trichromats have several different words for redgreen? (Orange, yellow and brown are also shades of redgreen, I think.)

    So how can there be an experience of redness when red is just a label I apply to one set of objects, and redgreen is a label my father applies (or might apply) to a different set of objects? At most you could say that different people have different (and as the example of my father and me shows, nonisomorphic) sets of qualia. But then they’re too idiosyncratic to say anything about at all, mere after-the-fact descriptions of arbitrary subsets of perceptions – and since they’re sealed off inside the mind of the being that has them or doesn’t, there’d be no way to know if you had built a zombie or not.

    In short, until you can define what it is that distinguishes a zombie from a non-zombie, you have no chance of distinguishing one from the other, let alone determining which (if either) is impossible. The whole question ultimately unravels on the failure to define the terms in which it is put.

    P.S. If you mean only that a creature with complex behavior must be able to categorize its perceptions and decide which ones are similar in important ways to which other ones, then I agree, but I see no reason to resort to mystic language like qualia to describe such an act.

  • http://www.daylightatheism.org Ebonmuse

    Hi Richard,

    Quick correction: some prominent philosophers think that the logical possibility of zombies refutes physicalism (even though zombies are of course nomologically impossible, and so could not be built in our world).

    Correct me if I’m wrong, but when we left off, you were explaining that some philosophers claim they can conceive of a world exactly like ours, with all the same physical laws, except lacking qualia, and asserting that this proves qualia must be non-physical. This still strikes me as a gigantic circular argument. I really don’t see how this is any different from a chemist, pre-Wohler, asserting the logical possibility of a world with all the same physical laws as ours, but no life, and concluding that this proves the existence of a supernatural vital force.

    Rastaban:

    We have scientific evidence for it in primates (chimps and humans) in the phenomenon of blindsight, for example.

    There are even stronger cases than blindsight that you could have mentioned. I’d have brought up the split-brain patients who appear to be able to perceive stimuli and correctly make judgments based on them, without being consciously aware of the reasons for their behavior. However, in those cases, it’s arguable whether we’ve created a zombie or just an additional stream of consciousness within the same brain which doesn’t have access to the voice box. (This is just a more specific example of the general problem of determining whether you’ve ever created a zombie, since by definition zombies are externally indistinguishable from conscious creatures like us.)

    Brad:

    Memory, understanding, and perception (in their cognitive forms) can all be emulated by a computer. In fact, in “Blockbuster,” you said

    “The ability of analysis is not a sufficient condition for consciousness, but it is clearly a necessary one.”

    That I did. But, as I recall, I also pointed out that a Blockhead (as well as its analogue, the Chance Conversation Machine, which simulates consciousness by using enormous resources of time rather than enormous resources of space) could never be built in our universe. They are logically possible, but not practically feasible, given the physical laws that hold sway in our cosmos. And that’s just what I said in this post: zombies may exist in other possible worlds with different physical laws, but not in this one. In this world, it’s a safe bet that anything which displays apparent understanding (passing a Turing Test, say) does so because it possesses genuine understanding.

  • Alex Weaver

    The only remaining question, which I admit is a vexing one, is: why qualia? Why does consciousness have any subjective character at all? The way in which our minds represent characteristics of the external world as ineffable interior perceptions does seem strange, and not like most other phenomena we encounter. It does indeed seem difficult to imagine that any science, however advanced, could explain precisely how such subjective experiences arise from the collisions of atoms inside the brain.

    While it’s nothing more than armchair musing, I was thinking about a comment I read somewhere about “color as a way of representing photon frequency data” and it occurred to me that one explantion of qualia in general is that they are a kind of internal “shorthand” – a way for the brain to form a useful approximation of amounts of data that are simply too vast to be processed at a realistic, useful rate in their “raw” form. Hence, our brain represents an array of photon frequency information as color for more or less the same reason my 3D CAD software represents a cylinder as a prism with a very large number of sides – a workaround for hardware limitations.

    (This hypothesis has the ironic implication that the idea many people have that qualia sensory experience is more “real” than abstract information about the same phenomenon is roughly 180 degrees wrong.)

  • http://geniusnz.blogspot.com GNZ

    Vitalism tends make claims about how a vital force creates ‘life’. Epiphenomenal Qualia doesn’t make any claim at all regarding any effects on the physical universe.

    regarding blindsight etc, Qualia are not a soul, they don’t have to have that sort of specific relationship. The Qualia theory is actually a less ambitious theory than most people assume.

  • http://www.daylightatheism.org Ebonmuse

    Petrucio: I don’t recall ever saying that humans were the only conscious species. I’ve always believed that most animals have qualia, even if theirs are probably somewhat different than ours (cf. “What is it like to be a bat?”). I don’t even think we’re the only self-conscious species. Animals like chimpanzees can pass a mirror self-recognition test, so I’m quite willing to grant that they must possess some form of self-consciousness, though it’s probably more rudimentary than ours.

    Our capacity for explicit representation in the form of language permits us to form a more detailed and reflective conception of our own selves than any other animal species. I note that animals like chimps, though they can readily learn symbolic representations like sign language, seem unable to grasp the concept of recursion that comes naturally to humans. They can express what they want or what they’re about to do, but they can’t nest sentences inside sentences (inside sentences inside sentences…) the way a human can. They can express “first-order” thoughts about the world and their own state, but apparently not second-order thoughts (thoughts about their own thoughts). That process of introspection is a vital component of self-aware consciousness, and non-human animals seem to have it to only a very limited degree.

  • http://www.bellatorus.com Petrucio

    I’m not so sure apes and maybe even some cetaceans (who can also pass a mirror test), do not have recursive language. So far we haven’t been able to find it, so it seems to be the current preferred ‘uniqueness’ of our species. Many uniquenesses have been proposed before, none was really that unique.

    I think the whole idea that we are somehow intrinsically better is crap, even if we are talking about our brains and language. We just crossed some very gray line that allowed us to write, and all hell broke loose after that. But we don’t need to postulate a new paradigm to do that, maybe just an increased processing power was enough.

  • Brad

    It looks like I obliviously misread the intent of this post. It was to answer the question, “Are Zombies Possible?”, instead of to argue monism. Instead, I took it as an argument against dualism. I tend to think that qualia and subjective experience is something other than matter or particle trajectories, hence they are two totally distinct types of things, or dualistic.

    I suppose even if I adhere to this dualism and observe that consciousness always appears to emerge from most brain-carrying humans (at least), I would have to make the naturalistic inference that, all else equal, consciousness cannot be “subtracted” without changing physical variables.

  • http://www.philosophyetc.net Richard

    This still strikes me as a gigantic circular argument.

    Maybe, but in any case it’s importantly different from the argument you discuss, and attribute to “some prominent philosophers”, that “we could build” a zombie. Nobody (not made of straw) makes that argument.

  • http://www.skepchick.com writerdd

    Actually, studies that have been done with people who have brain damage don’t show that zombies prove consciousness is supernatural or spiritual, but rather that is just part of brain function.

    For example, one person could not “see” an item that was thrown at them on the left side of their body. But they caught the item every time, preventing themselves from being injured, showing that they did actually see the item, but they were unaware of seeing it. In a sense, they were acting just like a zombie in this scenario. They had no qualia or consciousness of sensory input regarding the left side of their body, but the actually sensory input was there and working perfectly, even to the extent that it created the desired outcome: preventing injury.

  • http://www.philosophyetc.net Richard

    WriterDD – I wouldn’t say the perceptual capabilities of blindsight or split-brain patients were “working perfectly”. Only some aspects were. Other behavioural aspects, e.g. the capacity to verbally report what one is perceiving, were defective. So they are not really ‘zombies’ in the philosopher’s sense of beings that are physically and behaviourally indistinguishable from a conscious person.

    (So, ironically, it’s the very fact that you have some empirical grounds for thinking them non-conscious ‘zombies’ which guarantees that the attribution doesn’t quite fit.)

  • http://www.daylightatheism.org Ebonmuse

    I don’t agree that this is a straw man, Richard. For instance, what is David Searle’s Chinese Room if not a zombie? I don’t recall Searle ever stating that it would be impossible to build such a thing, only that it wouldn’t have subjective conscious experience if it was built. Similarly, there’s Ned Block’s China-body thought experiment. Granted there are some philosophers, such as David Chalmers, who believe zombies are impossible; but there are others who believe in the possibility of an actually existing being with absent qualia.

  • http://www.philosophyetc.net Richard

    But they think that’s because of the physical differences, so the object in question is no zombie (it lacks qualia, but it is not a physical duplicate of a conscious being). The rejection of Strong AI is perfectly compatible with physicalism.

  • http://www.skepchick.com writerdd

    Actually, Richard, I didn’t mean that to be an example of something working perfectly in entirety. But if we can show that many different aspects of the system are merely brain functions, then that implies that the whole system is a conglomeration of various brain functions. I was not trying to give an example of a person that is a zombie, because that would be impossible — we would, as others have mentioned, have no way to know. The only time we can see how the system functions is when part of it malfunctions. By seeing what makes it malfunction — that is, direct damage to the brain, not some sort of lack of spiritual activity — then we can say the functioning brain is what causes consciousness, not the presence of some sort of spiritual activity. On the other hand, if brain damage did not ever cause any changes in consciousness, we could come to the conclusion that consciousness was not a function of the brain, and it would be appropriate to look for another cause.

  • http://www.philosophyetc.net Richard

    we can say the functioning brain is what causes consciousness

    But nobody disputes that the physical substrate (e.g. brain) is necessary for consciousness. The question is whether it metaphysically suffices. Perhaps, as dualists contend, the brain gives rise to consciousness only because of certain extra-physical background conditions (e.g. psycho-physical bridging laws) that could have been absent.

  • http://geniusnz.blogspot.com GNZ

    before one surrenders the definition of zombie entirely I note the following.

    lets say there is a conceivable world with a bridging law such that the equivalent of a “zombie” created in our world (not a p-zombie by Richard’s definition) has qualia. An identical Richard in that world refers to that zombie in this world is a p-zombie while Richard here refers to the same zombie as not a p-zombie.

    as to disproving qualia, one can easily be lead on a wild goose chase – note that qualia are a effect not a cause and are vaguely defined. If you want to disprove such an idea you must either find an effect that contradicts our understanding of the world (but it has no physical effects) or prove an internal contradiction (which would require some detail on the nature of qualia).

  • TrekGirl

    We see colors: the redness of red, the greenness of green. We hear tones, sharp or high-pitched or dull or low. We taste flavors, salty or bitter or sweet. We feel emotions like joy, anger, or sadness. Zombies, by contrast, have none of these experiences.

    Neither did I after a few days on Zyrtec!

  • http://www.skepchick.com writerdd

    But nobody disputes that the physical substrate (e.g. brain) is necessary for consciousness. The question is whether it metaphysically suffices.

    Actually, you are mistaken.

    Professional philosophers may think that way, but dualists who are my neighbors and probably yours do not. They believe, for example, that the spirit (soul, consciousness, call it what you will) survives the death of the body. They do not believe that people with brain damage have lost their consciousness, but rather that their spirit/soul is just trapped in their bodies and unable to communicate to the outside world. They do not think that people with serious mental disabilities caused by the brain have any less of a “soul” than those of us with healthy brains; again the trapped in the body analogy is apt. Most “average joe” dualists do not think that consciousness depends upon brain function in any real or tangible way.

  • http://www.philosophyetc.net Richard

    Oh, yes, but “average joe dualists” are idiots; why would you waste your time arguing against them? It’s the strongest arguments for dualism that warrant your attention, at least insofar as you are interested in the truth of the matter.