Now of course we can’t launch Machines Q and Z at “the same instant”, because they belong to different universes with independent timelines, but luckily these two universes have exactly the same laws of physics, so synchronization isn’t necessary. We just start them up and let them do their things. As before, they do exactly the same thing, since they are both following the same laws of physics, and physics suffices to determine all behavior down to the finest detail. And yet, what do you suppose turns out to be the case? Oddly enough, although both machines do exactly the same thing down to the quark level and far beyond, Machine Q enjoys feelings about what it is doing while Machine Z does not. Machine Q is in fact ecstatic, whereas Machine Z feels nothing. That is, Zilch. Zero.
“How is that possible?”, you might ask. I too, no less bewildered, ask the same question. But Dave most cheerfully explains: “Oh, it’s because the universe in which Machine Q exists has something extra, on top of the laws of physics, that allows feelings to accompany certain types of physical processes. Even though these feelings don’t have and can’t have any effect on anything physical, they are nonetheless real, and they are really there.”
In other words, although physics is identical in Universes Q and Z, there are no feelings anywhere in Universe Z — just empty motions. Thus Machine Z mouths all the same words as Machine Q does. It claims to be ecstatic about its proof (exactly as does Machine Q), and it goes on and on about the beauty it sees in it (exactly as does Machine Q) — but in fact it is feeling nothing. Its words are all hollow.
Two Daves
What is this extra ingredient that makes Universes Q and Z so vitally different? Dave doesn’t say, but he tells us that it is the very stuff of consciousness — I’ll dub it élan mental — and if you’re born in a universe with it, then lucky you, whereas if you’re born in a universe without it, well, tough luck, because there’s no you-ness, no I-ness, no who-ness, no me-ness (or he-ness or she-ness) in you — there’s just it-ness. Despite this enormous difference, all the objective phenomena in both universes are identical. Thus there are Marx Brothers movies in both of these universes, and when Z-people in Universe Z look at A Night at the Opera, they laugh exactly the same as when Q-people in Universe Q look at A Night at the Opera.
Most deliciously ironically of all, just as there is a Dave Chalmers in Universe Q (the one in which we live), there is also a Dave Chalmers in Universe Z, and it goes around the world giving lectures on why there is feeling in the universe in which it was born but no feeling in the isomorphic universe into which its unfortunate “zombie twin” was born. The irony, of course, is that Universe Z’s Dave Chalmers is lying through its teeth, yet without having the foggiest idea it’s lying. Although it believes it is conscious, in truth it is not. Sadly, this Dave is an innocent victim of the illusion of consciousness, which is nothing but a trivial by-product of having a deeply entrenched strange loop in its brain, whereas its isomorphic counterpart in Universe Q, using the same words and intonations, is telling the truth, for he truly is conscious! Why? Because he not only has a strange loop in his brain but also — lucky fellow! — lives in a universe with élan mental.
Now please don’t think I am poking fun at my friend Dave Chalmers, for Dave truly does go around the world visiting philosophy departments, giving colloquia in which he most gleefully describes his “zombie twin” and chortles merrily over that twin’s helpless deludedness, since the zombie twin gives word for word and chortle for chortle the very same lecture, believing every word of it but not feeling a thing. Dave is a very insightful thinker, and he is every bit as aware as I am of the seeming craziness of his distinction between Universes Q and Z, between Machines Q and Z, and between himself and his alleged zombie twin, but whereas I find all of this unacceptably silly, Dave is convinced that, outrageous though such a distinction seems at first to be, Universe Q’s mysterious, nonphysical, and causality-lacking extra ingredient élan mental — a close kin to the notion of “feelium” discussed by Strange Loops #641 and #642 — is the missing key to the otherwise inexplicable nature of consciousness.
The Nagging Worry that One Might Be a Zombie