More on Zombies

In my last post I discussed David Chalmer’s idea of philosophical zombies – hypothetical creatures whose brains have precisely the same physical structures as ours and function in the same ways that our brains do, but without consciousness. Several people who read early drafts of my book, Your Living Mind, dismissed zombies as irrelevant. The whole idea is moot, one of them remarked, since it would be impossible for us to know that such a creature is a zombie. (Maybe the person sitting right next to you is one of them!) But Chalmers’ scenario is an example of both the value and the subtlety of thought experiments. If there actually could be such creatures, then conscious experiences are not brain events.

The zombie story asserts that if there could be a creature that is physically identical to you, but not conscious, then consciousness is not a state of your brain. We could dispute this claim by arguing that even though a creature physically identical to you could exist without being conscious, nevertheless consciousness is a state of your brain. But that won’t work. Let’s call your current brain state CBS. If your brain’s being in state CBS is sufficient for your being conscious, then if some other brain is in CBS, it would also have to be conscious. So you could not have a physically identical zombie twin. (What a relief!) On the other hand, if a brain’s being in state CBS is not sufficient for its being conscious, then consciousness is not a brain state. We would need a brain state plus something else to have consciousness – or we would just need the “something else.” So if zombies are truly possible, qualia are not brain states. Since there has been a strong trend toward saying that all real things are, in some sense, physical, that would be a revolutionary finding.

Michael Tye clarifies Chalmers’ idea with an omnipotent-being scenario. “One way to picture what is being claimed here is to imagine God laying out all the microphysical phenomena throughout the universe. Having done so, and having settled all the microphysical properties of those phenomena along with the basic microphysical laws, God did not then have to ask Himself ‘Shall I make lightning flashes or caterpillars or mountains … ?’ No further work was needed on His part.” Why? Because a lightning flash simply is a group of microphysical entities operating according to certain laws. By making all these particles and deciding how they would interact, the Creator would have ensured that lightning flashes, caterpillars, etc. would exist.

But what if consciousness is not physical? In that case zombies are possible. “Even if God had no further work to do in determining whether there would be a tree in place p or a river in place q or a neuron-firing in place r, say, having settled all the microphysical facts, God did have more work to do to guarantee that we were not zombies.”*

Tye is not trying to show that a deity created consciousness. That’s not the point. He’s just noting that this is one way of understanding Chalmers’ scenario. Conceivably, then, there could be an exact physical duplicate of you, right down to the last whirling electron, that does not enjoy a single millisecond of conscious experience.

Chalmers emphasizes that he is not trying to prove that a zombie duplicate of you or me could really exist in this universe – only that this sort of thing is conceivable. But what does “conceivable” mean? Now the fog drifts in. There are several types of conceivability, including a contentious notion called “ideal conceivability.” Philosophical professionals have not yet sorted out these intricacies.

In trying to solve the hardest problems of consciousness we seem to be perpetually stuck at square one. Nagel has stated bluntly that “we have at present no conception of what an explanation of the physical nature of a mental phenomenon would be. Without consciousness the mind-body problem would be much less interesting. With consciousness it seems hopeless.”** And William Seager concludes his book, Theories of Consciousness, with this dispirited admission: “It is indecent to have a ragged and unpatchable hole in our picture of the world. Cold comfort to end with the tautology that an unpatchable hole is … unpatchable.”***

To some it seems as if these scholars are worrying about trivialities, as irrelevant as asking how many angels can dance on the head of a pin. But some questions about the nature of reality actually are quite difficult. I have my own ideas about how to understand consciousness, but on some level I must also bow to this great mystery.

Roger Christan Schriner

*Michael Tye (2009) Consciousness Revisited: Materialism without Phenomenal Concepts. (Cambridge, MA: The MIT Press), pp. 25-26.

**Thomas Nagel (1974) “What Is It Like to Be a Bat?” Philosophical Review, October, 1984, Vol. 83, No. 4, p. 436.

***William Seager (1999) Theories of Consciousness: an Introduction and Assessment. (New York: Routledge), p. 252. Ellipses are in the original text.

The Philosophical Zombie

Can old bedraggled zombies reflect logically on their condition and calmly resign themselves to their fate? Perhaps, but that’s not what this post is about. In the study of consciousness, philosophical zombies were first described in a famous thought experiment by Australian philosopher David Chalmers. His discussion helps underscore the mysterious nature of qualia (the qualities of sensory experiences).

Chalmers proposed the zombie idea to highlight the Hard Problem of consciousness, the problem of understanding how conscious experiences result from (or are identical to) brain activities. A philosophical zombie is a hypothetical creature whose brain has precisely the same physical structures as ours and operates in the same ways that our brains do, but without consciousness.

Here’s an important point that is often overlooked: This creature would be conscious in the ways that psychology understands the structures, abilities, and functions of consciousness. “He will be awake, able to report the contents of his internal states, able to focus attention in various places, and so on.”* Furthermore a psychologist studying you and your zombie twin would discern no difference in behavior. But even though it would be conscious in a certain sense, it would lack conscious experiences. It would be utterly devoid of qualia, and it would never be in any state that is “like something.”

Thus, as Philip Goff notes, when it screams it is not in pain. “Its smiles are not accompanied by a feeling of pleasure. Its negotiation of its environment does not involve a visual/auditory experience of that environment.”**

Although zombies would have thoughts, these thoughts would not involve conscious perceptions or sensations. A zombie that is screaming might think, “I’m in pain!” but it would have no pain qualia, no conscious sensations of pain. This is an example of the important difference between aspects of consciousness that do and do not seem “present.” The philosophically puzzling states are the ones that seem thus-there-now, and zombies don’t have them.

I’ll allow a few days for comments about these hypothetical organisms, and then journey further into zombieland.

Roger Christan Schriner

*David Chalmers, The Conscious Mind. (Oxford: Oxford University Press), p. 95. Technical note: Chalmers was suggesting that there is an ontological gap between conscious experiences and brain states, not just the sort of epistemic gap that Joseph Levine has discussed. In other words, qualia and brain states don’t just seem different; they really are quite different. In this way Chalmers was following in the footsteps of Saul Kripke, whereas Levine was trying to avoid Kripke’s ontological conclusions.

**Philip Goff, “The Zombie Threat to a Science of Mind,” Philosophy Now, May/June, 2013: Goff provides an engaging and detailed explanation of the zombie problem, graced with charming color illustrations of non-philosophical zombies.

The Dreaded “Hard Problem”

I’ve been posting thoughts about “qualia,” the qualities of sensory experience. Qualia figure prominently in one of the most baffling enigmas even discussed, and the history of this issue is wonderfully described by Oliver Burkeman. I’ll quote some of his essay, but I urge you to read the whole thing:

“One spring morning in Tucson, Arizona, in 1994, an unknown philosopher named David Chalmers got up to give a talk on consciousness…. the young Australian academic was about to [discuss] a central mystery of human life – perhaps the central mystery of human life – and revealing how embarrassingly far they were from solving it.

“The scholars gathered at the University of Arizona … knew they were doing something edgy: in many quarters, consciousness was still taboo, too weird and new agey to take seriously, and some of the scientists in the audience were risking their reputations by attending. Yet the first two talks that day, before Chalmers’s, hadn’t proved thrilling. ‘Quite honestly, they were totally unintelligible and boring – I had no idea what anyone was talking about,’ recalled Stuart Hameroff, the Arizona professor responsible for the event. … ‘But then the third talk, right before the coffee break – that was Dave.’ With his long, straggly hair and fondness for all-body denim, the 27-year-old Chalmers looked like he’d got lost en route to a Metallica concert. … ‘But then he speaks. And that’s when everyone wakes up.’

“The brain, Chalmers began by pointing out, poses all sorts of problems to keep scientists busy. How do we learn, store memories, or perceive things? How do you know to jerk your hand away from scalding water, or hear your name spoken across the room at a noisy party? But these were all ‘easy problems’, … given enough time and money, experts would figure them out. There was only one truly hard problem of consciousness, … why on earth should all those complicated brain processes feel like anything from the inside? Why aren’t we just brilliant robots, capable of retaining information, of responding to noises and smells and hot saucepans, but dark inside, lacking an inner life? …’

“What jolted Chalmers’s audience from their torpor was how he had framed the question. ‘At the coffee break, … everyone was like: “Oh! The Hard Problem! The Hard Problem! That’s why we’re here!”’

Here’s one way of considering this issue. Suppose in the distant future neuroscience has discovered precisely which brain structures and processes are correlated with specific conscious experiences. They can even read people’s minds: Experimental subject C79 reports that she is recalling a teenage love affair. But a brain scanning machine had already printed out a report, just before C79 spoke: “subject is remembering a high school sweetheart.” Isn’t it clear that we now understand the neural basis of consciousness? Aren’t the neural structures and activities that the scanner detected simply identical to the memory-experience that C79 reported?

Not necessarily. We need to know why this configuration of neural structures and activities constitutes consciousness. “Even if every behavioral and cognitive function related to consciousness were explained,” writes Chalmers, “there would still remain a further mystery: Why is the performance of these functions accompanied by conscious experience? It is this additional question that makes the hard problem hard.”*

Next: the menace of philosophical zombies.

Roger Christan Schriner

*Cited by Uriah Kriegel, Subjective Consciousness: A Self-Representational Theory, p. 271, emphasis added.

The Economist Investigates Consciousness

Today I’ll take a break from discussing Six Persistent Enigmas about Consciousness, to comment on The Economist’s recent series on six great mysteries of science. I highly recommend these thoughtful and fact-filled two-page essays, and the final installment (September 12) is titled:

“What is consciousness? The hard problem”

There’s a lot of good material in this piece, but journalism often contains mistakes, even in a respected periodical such as The Economist. A few examples:

“Subjective though it is, consciousness … looks like a specific phenomenon, not a mere side-effect.” But of course side effects can be “specific.”

I think it’s fairly obvious that being conscious, in the sense of having vivid, sensuous, introspectible experiences, is quite different from being self-conscious, in the sense of being aware of oneself. In all probability, many animals that lack self-consciousness are perceptually aware of their surroundings and their own body-sensations. But the article muddles these two uses of the term “consciousness” repeatedly.

Some people with damaged visual cortices have “blindsight.” They report that they cannot see anything in large areas of the visual field, but if they are asked a yes-no question about the “blind” part of their visual field they can often answer correctly – e.g., “Did a light flash just now?” I have never heard of blindsighters spontaneously reaching out and picking up things they cannot see. But The Economist claims they can “point to, and even grasp, objects in their visual fields.” (If researchers have found blindsighters who do that spontaneously, without being cued, I am happy to be corrected, but I’m skeptical.)

These criticisms aside, the whole series is worth seeking out, and it is complimented by a series of brief videos. The video on consciousness showcases major scientists and philosophers such as Christof Koch, David Chalmers, and Daniel Dennett. See

Roger Christan Schriner