Douglas Hofstadter - I Am a Strange Loop

Two Machines

Dave Chalmers explores these issues in an unprecedented new fashion. He paints a picture of a world that has two machines identical down to the last nail, transistor, atom, and quark, and these two machines, sitting side by side on an old oaken table in Room 641 of the Center for Research into Consciousness and Cognetics at Pakistania University, are carrying out exactly the same task. For concreteness’ sake, let’s say both machines are struggling to prove, using informal geometrical insights rather than formal algebraic manipulations, the simple but surprising “chord–angle theorem” of Euclidean geometry, which states that if a point ( A in the figure below) moves along an arc of a circle, then the angle ( α ) subtended by a fixed chord ( BC ) that the point is “looking at” as it moves along will be constant.

I chose this elementary but elegant theorem because it is one that Dave and I discussed together with great pleasure many years ago, and some of his comments on it gave me insights that literally changed my life. In fact, that fateful fork in the road way back when allows me to imagine Switch #6, the throwing of which would subtract from my brain all knowledge of this theorem and all the subsequent passion for geometry that was sparked by my thinking carefully about it…

As I was saying, these two exactly identical machines are launched on this task in the exact same terasecond by an atomic clock, and they proceed in exact lockstep synchrony towards its solution, simulating, let us say, the exact processes that took place in Dave Chalmers’ own brain when he first found an insight-yielding visual proof. The details of the program running in both machines are of no import to us here; what does matter is that Machine Q (it stands for “qualia”) is actually feeling something, whereas Machine Z (it rhymes with “dead”) is feeling nothing. This is where Dave’s ideas grow incomprehensible to me.

Now I have to admit that in order to make it a bit easier to envision, I have slightly altered the story that Dave tells. I placed these two machines side by side on the old oaken table in Room 641 of CRCC, while Dave never does that. In fact, he would protest, saying something such as, “It’s bloody incoherent to postulate two identical machines running identical processes on the very same oaken table with one of them feeling something and the other one not. That violates the laws of the universe!”

I fully accept this objection and plead guilty to having distorted Dave’s tale. To atone for my sin and to turn my story back into his, I first remove one of the machines from the old oaken table in Room 641. Let’s call the machine who remains, no matter what we’d called it before, “Machine Q”. Now (following Dave), we take a rather unexpected step: we imagine a different but isomorphic ( i.e., “separate but indistinguishable”) universe. We’ll call the first one “Universe Q” and the new one “Universe Z”. Both universes have exactly the same laws of physics, and in each universe the laws of physics are all one needs to know in order to predict what will happen, given any initial configuration of particles.

When I say these two universes are indistinguishable, one of the myriad consequences is that Universe Z, just like Universe Q , has a Milky Way galaxy, a star therein called “Sol” with a nine-planet solar system whose third planet is called “Earth”, and on Universe Z’s Earth there is a Pakistania University with a Center for Research into Consciousness and Cognetics, and in it, good old Room 641. There is even “the same” old oaken table, and there, lo and behold, is “the same machine” sitting on it. Surely you see it, do you not? But since this machine is in Universe Z, we will call it “Machine Z”, just so that we have different names for these indistinguishable machines located in indistinguishable surroundings.

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.