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| Zombies are essentially machines that appear human. |
By Keith Tidman
Some philosophers have used the notion of ‘philosophical zombies’ in a bid to make a point about the source and nature of human consciousness. Have they been on the right track?
One thought experiment begins by hypothesising the existence of zombies who are indistinguishable in appearance and behaviour from ordinary people. These zombies match our comportment, seeming to think, know, understand, believe, and communicate just as we do. Or, at least, they appear to. You and a zombie could not tell each other apart.
Except, there is one important difference: philosophical zombies lack conscious experience. Which means that if, for example, a zombie was to drop an anvil on its foot, it might give itself away by not reacting at all or, perhaps, very differently than normal. It would not have the inward, natural, individualised experience of actual pain the way the rest of us would. On the other hand, a smarter kind of zombie might know what humans would do in such situations and pretend
Accordingly, philosophical zombies lead us to what’s called the ‘hard problem of consciousness’, which is whether or not each human has individually unique feelings while experiencing things – whereby each person produces his or her own reactions to stimuli, unlike everyone else’s. Such as the taste of a tart orange, the chilliness of snow, the discomfort of grit in the eye, the awe in gazing at ancient relics, the warmth of holding a squirming puppy, and so on.
Likewise, they lead us to wonder whether or not there are experiences (reactions, if you will) that humans subjectively feel in authentic ways that are the product of physical processes, such as neuronal and synaptic activity as regions of the brain fire up. Experiences beyond those that zombies only copycat, or are conditioned or programmed to feign, the way automatons might, lacking true self-awareness. If there are, then there remains a commonsense difference between ‘philosophical zombies’ and us.
Zombie thought experiments have been used by some to argue against the notion called ‘physicalism’, whereby human consciousness and subjective experience are considered to be based in the material activity of the brain. That is, an understanding of reality, revealed by philosophers of mind and neuroscientists who are jointly peeling back how the brain works as it experiences, imagines, ponders, assesses, and decides.
The key objection to such ‘physicalism’ is the contention that mind and body are separable properties, the venerable philosophical theory also known as dualism. And that by extrapolation, the brain is not (cannot be) the source of conscious experience. Instead, it is argued by some that conscious experience — like the pain from the dropped anvil or joy in response to the bright yellow of fields of sunflowers — is separate from brain function, even though natural law strongly tells us such brain function is the root of everyone's subjective experience.
But does the ‘philosophical zombie’ argument against brain function being the seed of conscious experience hold up?
After all, the argument that philosophical zombies, whose clever posing makes us assume there are no differences between them and us, seems problematic. Surely, there is insufficient evidence of the brain not giving rise to consciousness and individual experience. Yet, many people who argue against a material basis to experience, residing in brain function, rest their case on the notion that philosophical zombies are at least conceivable.
They argue that ‘conceivability’ is enough to make zombies possible. However, such arguments neglect that ‘being conceivable’ is really just another expression for something ‘being imaginable’. Isn’t that the reason young children look under their beds at night? But, is being imaginable actually enough to conclude something’s real-world existence? How many children actually come face to face with monsters in their closets? There are innumerable other examples, as we’ll get to momentarily, illustrating that all sorts of irrational, unreal things are imaginable — in the same sense that they’re conceivable — yet surely with no sound basis in reality.
Proponents of conceivability might be said to stumble into a dilemma: that of logical incoherence. Why so? Because, on the same supposedly logical framework, it is logically imaginable that garden gnomes come to life at night, or that fire-breathing dragons live on an as-yet-undiscovered island, or that the channels scoured on the surface of Mars are signs of an intelligent alien civilisation!
Such extraordinary notions are imaginable, but at the same time implausible, even nonsensical. Imagining something doesn’t make it so. These ‘netherworld notions’ simply don’t hold up. Philosophical zombies arguably fall into this group.
Moreover, zombies wouldn’t (couldn’t) have free will; that is, free will and zombiism conflict with one another. Yes, zombies might fabricate self-awareness and free will convincingly enough to trick a casual, uncritical observer — but this would be a sham, insufficient to satisfy the conditions for true free will.
The fact remains that the authentic experience of, for example, peacefully listening to gentle waves splashing ashore cannot happen if the complex functionality of the brain were not to exist. A blob that only looks like a brain (as in the case for philosophical zombies) would not be the equivalent of a human brain if, critically, those functions were missing.
It’s those brain functions that, contrary to theories like dualism, assert the separation of mind from body, that make consciousness and individualised sentience possible. The emergence of mind from brain activity is the likeliest explanation of experienced reality. Contemporary philosophers of mind and neuroscientists would agree on this, even as they continue to work jointly on figuring out the details of how all that happens.
The idea of philosophical zombies existing among us thus collapses. Yet, very similar questions of mind, consciousness, sentience, experience, and personhood could easily pop up again. Likely not as recycled philosophical zombies, but instead, as new issues arising longer term as developments in artificial intelligence begin to match and perhaps eventually exceed the vast array of abilities of human intelligence.
