What is the philosophical Zombie? How does it apply to the real world?
Answer by Geoffrey Klempner
If you want to read up on the literature for the ‘philosophical zombie’ a good starting point would be the Stanford Encyclopedia article by Robert Kirk.
I won’t venture into a summary or critique of that article. Instead, I will give my take on the zombie question and you can compare the two to see which you like better.
There are two connected points raised by the ‘zombie’ idea in philosophy. The first has to do with how I know that another person has an inner life or consciousness (the so-called ‘problem of other minds’). The second arises in an argument against the idea that consciousness is nothing more than a process in the physical brain, or ‘physicalism’ as this theory is called.
However, we need to not lose our bearings. In the ‘real world’ there are no zombies, philosophical or otherwise. It’s a fantasy notion. Dr Frankenstein’s monster in Mary Shelley’s novel is a zombie, i.e. a reanimated corpse (strictly speaking, the monster is stitched together from several corpses but the difference isn’t important).
You know that you’re dealing with a zombie because its behaviour just isn’t normal. It walks in a jerky way. When you shoot it with your pistol (as in the classic Romero movies) it just keeps on coming. But does it have to be that way? If we’re into the realms of fantasy, couldn’t a zombie be very hard to tell from a human being? or maybe impossible? Maybe I am a zombie. Maybe you are a zombie.
If I am a zombie, how come I am writing this? Zombies can’t speak let alone write. Ah, but a philosopher will tell you that the point is that the ‘essence’ of zombiehood isn’t in abilities or behaviour but rather what’s going on inside.
If I can’t tell from behaviour or any physical signs whether or not a person is a zombie, then I could be the only human being with consciousness. Maybe everyone else on Earth is a zombie. Then again, there could be someone just like me on ‘Twin Earth’ orbiting on the opposite side of the Sun who is a zombie. Physically, we are the same but I have consciousness and my zombie doppelganger does not.
I think this is nonsense. Sheer piffle.
How do I know this? I am going to ask my zombie double on Twin Earth what he thinks. He and I are physically the same, behave exactly the same way, say exactly the same things. So, in response to my question, my zombie double will say, ‘I know I have consciousness but maybe you’re a zombie!’
We both say, ‘I know I have consciousness’, because our brains work in exactly the same way, producing exactly the same physical results. I can try as hard as I like to ‘point’ to my own inner state of consciousness while I am saying, ‘I know I have consciousness’, but in terms of cause and effect the words you hear have nothing to do with what I am trying to describe. They don’t come from ‘inside’, they come from my brain. Something (I have no idea what) in my physical brain makes them come. Whatever is going on ‘inside me’ is not playing any role in this story.
That doesn’t absolutely disprove the zombie idea, but it comes close. Close enough to say that any philosopher who bandies about the word ‘zombie’ doesn’t know what they’re saying. They imagine something, but what they imagine amounts to no more than a mute gesture, like pointing to your head with an urgent expression on your face. Inside! Inside!
I noted that if there could be a philosophical zombie, then physicalism is false. If there could be a zombie, then consciousness is something extra, on top of anything physical. However, it would be an obvious logical fallacy to conclude that because the idea of a philosophical zombie is nonsensical, physicalism is true after all. That doesn’t follow.
Let’s look again at my doppelganger on Twin Earth. He isn’t a zombie. He has consciousness just like me. But even though he is writing these very same words as I am writing at this very moment, he is not I. He is another ‘I’. That shows something. We have two identical physical beings, two ‘I’s. I could be one or the other. But why should I be either? What could possibly explain why one of these beings, but not the other, is I? It can’t be anything physical, by hypothesis. (The form of argument I’ve used here was known in Ancient philosophy as ou mallon, or the ‘no more reason’ principle.)
If physicalism can’t explain why I am I, then physicalism can’t be true. That’s the conclusion I came to in my recent article for Philosophy Pathways. There is more on this in my previous answer, below.