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.


Your Sensory Experiences: Are They in Your Head or Out There in the World?

Suppose you’re at a jazz concert. You notice horn-like noises, along with what seems to be a visual image of someone working the slider of a bright, brassy trombone. Here are two ways of thinking about this episode, assuming that you are perceiving accurately rather than hallucinating.

❁ You are directly perceiving someone playing a trombone.
❁ You are inwardly experiencing sounds and sights, which leads you to infer that someone is playing a trombone. This inference happens with such lightening speed that you don’t even notice it. All you notice is that you’re seeing and hearing a trombone solo.

On the second interpretation, we do not directly perceive the world. Instead we are aware of an inner simulation of worldly objects, and we treat this simulation as if it were real.

Phenomena such as horn-sounds and the visual image of a musician have sometimes been called sense data. Some advocates of “indirect realism” claim that we know sense data directly, and this indirectly informs us about real events in the outside world.

In the early Twentieth Century many indirect realists thought sense data were non-physical, following in the footsteps of Seventeenth Century philosopher René Descartes. But this “Cartesian” view has been rejected by those who believe that everything is made of matter. To them, speaking of immaterial substances such as sense-data sounds like mumbo-jumbo. So indirect realism has acquired a rather bad odor these days, especially if it even hints at sense data. An influential paper by Gilbert Harman disparaged the “notorious sense datum theory.” ( Uriah Kriegel reports that indirect realism “is widely regarded as bankrupt …” (Subjective Consciousness, p. 225).

Many scholars have now abandoned the “internalist” idea that experiences are inside of us. Marching under the banner of externalism, they contend that conscious experiences only inform us about things in the outside world. Michael Tye, for example, has famously proclaimed that “[sensory] phenomenology ain’t in the head.” (Ten Problems of Consciousness, p. 151.) He concludes a recent book by calling scholars to the barricades:

“For the thoroughly modern materialist, the thesis of phenomenal internalism … should be ‘committed to the flames.’ Only then will all vestiges of Cartesianism be eliminated from the materialist worldview.”(Consciousness Revisited, p. 199)

In asking whether consciousness could be a brain event, we are actually dealing with two questions:

❁ Why don’t conscious experiences seem like brain events?
❁ Why does it seem as if they are definitely not brain events?

Obviously conscious experiences do not grant us admission to the nonstop party our neurons are having in our skulls. Nevertheless, experiences could consist of brain activity even though we cannot introspect them as brain activity. This may be no more mysterious than looking at a river or a geranium without detecting the atoms of which they are composed. In this blog I will mostly focus on the more difficult question – why sensory experiences seem to almost shout that they are not brain events.

When someone enjoys the sights and sounds of a concert, the smell and taste of pecan pie, or the tingle of a caress, are these experiences mental events? Are they the direct detection of objects in the world? Or both? Or neither? What do you think – and why?

Roger Christan Schriner

To subscribe to this blog, click the “Follow” link which is typically located on the upper left.