Chalmers, now 48, recently cut his hair in a concession to academic respectability, and he wears less denim, but his ideas remain as heavy-metal as ever. The zombie scenario goes as follows: imagine that you have a doppelgänger. This person physically resembles you in every respect, and behaves identically to you; he or she holds conversations, eats and sleeps, looks happy or anxious precisely as you do. The sole difference is that the doppelgänger has no consciousness; this – as opposed to a groaning, blood-spattered walking corpse from a movie – is what philosophers mean by a “zombie”.
Such non-conscious humanoids don’t exist, of course. (Or perhaps it would be better to say that I know I’m not one, anyhow; I could never know for certain that you aren’t.) But the point is that, in principle, it feels as if they could. Evolution might have produced creatures that were atom-for-atom the same as humans, capable of everything humans can do, except with no spark of awareness inside. As Chalmers explained:Oliver BurkemanI’m talking to you now, and I can see how you’re behaving; I could do a brain scan, and find out exactly what’s going on in your brain – yet it seems it could be consistent with all that evidence that you have no consciousness at all.If you were approached by me and my doppelgänger, not knowing which was which, not even the most powerful brain scanner in existence could tell us apart.
If you find yourself struggling with the novel Blindsight, this article might help – a bit. It goes through all the conflicting views of scientists and philosophers on an age-old human question. Is consciousness another force of nature, the immaterial substance of the soul? A false dilemma, caused by our fragmentary understanding of the brain? Or an inherent quality of the universe like mass or electrical charge? A Hard Problem indeed.On the same note: a short story in (exactly) 500 words by Alastair Reynolds: The Face in the Machine.