(from today’s “Zombie Zymposium”)

I’d like to discuss two things. First, I’ll discuss the quasi-technical use of “zombies” in recent discussions of the philosophy of consciousness. I’ll call these entities “philosophical zombies” since, as we’ll see, they are not much like the zombies more commonly featured in movies and TV shows. Secondly, I’d like to speculate about the cultural significance of philosophical zombies – specifically, what discussions of them reveal about our culture.

A philosophical zombie is an allegedly conceivable entity that is meant to show that physicalism is false. Physicalism is the view that human consciousness can be explained through neuroscience, or through the study of the physical properties and events of the brain. If physicalism is true, then physical accounts of the brain/body should be able to explain why we have particular sensations and experiences; brain science should tell us exactly why the brain undergoing some particular event will result in us tasting pineapple or smelling rotten eggs. If it is a real explanation, then we should be able to see why anyone with a brain in that particular state would have that particular experience.

Enter the philosophical zombie. Such a zombie is defined as a creature that is just like us in terms of physical properties. It also is just like us in terms of behavior, including speech behavior. But they are different from us in the fact that they have no conscious experience. The lights are on, but nobody is home. It is not like anything to be them. They are like incredibly complex robots, or wind-up toys, with no first-person perspective or feelings or thoughts whatsoever.

So: is it possible to conceive such a being? Note that I am not asking if there are any zombies, or if we can make one. I’m only asking if we can conceive of such a being without encountering any contradiction. We can’t conceive a four-sided triangle, or a married bachelor, or a nephew whose parents have no siblings. We can conceive a mile-high unicycle, or a bear with six legs, or a snowball not melting on a very hot day in July. So is a philosophical zombie like a four-sided triangle or a six-legged bear? Is it something we can conceive?

If we can, the argument goes, then physicalism is false. For then we can conceive a brain doing all the stuff brains typically do without there being any conscious experience. And if we can conceive that, then an account of what the brain is doing when we have a particular conscious episode does not explain why we should be having that particular episode rather than another, or rather than none at all. The zombie is a conceivable case in which the brain is doing its thing, but no conscious event is happening. If that’s conceivable, then physicalism hasn’t provided a real explanation. At most, it’s pointed out a mysterious correlation between conceptually distinct events.

But what then is true, if physicalism isn’t? Here philosophers have resisted the temptation to believe in souls, or immaterial things that have experiences. They have instead suggested that conscious experience is a hidden dimension of the physical, or that nature includes both physical and nonphysical properties, or that some physical events can somehow give rise to conscious states. In short, they have tended to reach for pixie dust.

Now the most promising response on the part of the physicalist is to insist that no, zombies are not conceivable. It seems like they are, but they’re not. Daniel Dennett makes this case by ramping up our concept of a zombie into a zimbo: a zimbo is a zombie that can adjust its behavior on the basis of monitoring its own behavioral states. It’s still not conscious, mind you. But it can see what it is doing, hear what it is saying, gain feedback from the environment, positive or negative, and adjust its behavior accordingly. If you are having trouble imagining such a being without attributing consciousness to it, then Dennett says you are discovering that philosophical zombies are in fact inconceivable. Indeed, he writes, there is a sense in which we are all zombies – namely, in the sense that there is nothing to us over and above our brain behavior and bodily behavior that gives us the experience we have. Physicalism is the view that we are zombies.

Now why on earth are philosophers devoting so much attention to zombies? To a large extent, surely, it is to determine whether physicalism is true. It’s philosophical curiosity. But there’s always more than that going on.

Philosophical zombies started to receive lots of attention in the mid 1990s. At this point in time, computers were becoming more widespread, more powerful, and more interesting; the discussions about artificial intelligence were becoming less science-fictiony and more science-facty. So there was a general awareness that a physicalistic account of consciousness might be genuinely possible. Then again, that had been true since at least the 1950s, and maybe since the 1650s.

But I think other factors were responsible for the sudden emergence (or re-emergence) of philosophical zombies. The mid-1990s marked the end of the cold war and a kind of triumph of the Reagan/Thatcher/Bush-the-elder political regimes. In the eyes of liberal college professors (at least), these regimes promoted and rewarded a kind of opportunism and corporate greed that had been largely suppressed or regulated over the previous eight decades. The “Yuppie” (Young Urban Professional) became for many a genuine societal ideal, though this ideal was met by liberals with large measures of scorn, disdain, and satire. In this vein, one of the most powerful TV commercials ever produced accused corporate-driven consumerist society of being the totalitarian state envisioned by George Orwell in 1984.

Now the irony should be lost on no one that this commercial was for Apple, which was itself a totalitarian regime, and it was taking aim at another totalitarian regime, IBM, which at that time served as the whipping boy for MBA-style lack of creativity. (Then Microsoft stepped into that particular role.) But the commercial cleverly played upon a general yearning among liberal consumers to see themselves as more than faceless cogs in dreadful machines: to see themselves, that is, as something other than mere robotic servants, or zombies.

I believe that the “philosophical zombie phenomenon” in the 1990s and 2000s gained its momentum from a liberal yearning among philosophers to see themselves as creative agents (led by David Chalmers, at that time a young, long-haired, brilliant upstart from Down Under), and a yearning to see human consciousness generally as itself special and irreducible to material forces. It was a kind of rebellion against a staid philosophical tradition, but also against a broader society that was celebrating conformity and materialistic consumerism. The confidence that zombies are metaphysically possible was fueled by the recognition that corporate zombies were actually all over the place, and by the fear of becoming one.

Seen in this light, the reactionary response from physicalists – that “We are all zombies!” – can be heard as the voice of the disillusioned, the Microsoft confidence that Excel spreadsheets are, in the end, more bankable than iPaint. Nothing human offers lasting resistance to the scientistic effort to reductively explain. The pixie dust, we are brutally informed, is just dust.

In all this, I’m half-joking, but only half. It’s certainly not true that nonphysicalists in philosophy of mind are all political liberals, and physicalists are political conservatives. But in all of us there are propensities to think magically alongside enlightened demands that we not dream, and that we face facts as they are. These inner drives fuel debates about human consciousness just as they fuel political disputes.

A thought experiment is never just a thought experiment.