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 (
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
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 (
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
“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
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
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
Most deliciously ironically of all, just as there is a Dave Chalmers in Universe Q (the one in which
Now please don’t think I am poking fun at my friend Dave Chalmers, for Dave truly
The Nagging Worry that One Might Be a Zombie
Of late, not a few philosophers of mind have, like Dave, been caught in a tidal wave of fascination with this notion called “zombies”. (Actually, it’s more like “the notion we love to hate”.) It seems to have originated in voodoo rites in the Caribbean and to have spread from there to horror films and then to the world of literature. A Web search will quickly give you all the information you want, and most of it is pretty funny.