(ETA: I’ve cre­ated three threads—color, com­pu­ta­tion, mean­ing—for the dis­cus­sion of three ques­tions posed in this ar­ti­cle. If you are an­swer­ing one of those spe­cific ques­tions, please an­swer there.)

I don’t know how to make this about ra­tio­nal­ity. It’s an at­tack on some­thing which is a stan­dard view, not only here, but through­out sci­en­tific cul­ture. Some­one else can do the met­alevel anal­y­sis and ex­tract the ra­tio­nal­ity les­sons.

The lo­cal wor­ld­view re­duces ev­ery­thing to some com­bi­na­tion of physics, math­e­mat­ics, and com­puter sci­ence, with the ex­act com­bi­na­tion de­pend­ing on the per­son. I think it is man­i­festly the case that this does not work for con­scious­ness. I took this line be­fore, but peo­ple strug­gled to un­der­stand my own spec­u­la­tions and this com­pli­cated the dis­cus­sion. So the fo­cus is go­ing to be much more on what other peo­ple think—like you, dear reader. If you think con­scious­ness can be re­duced to some com­bi­na­tion of the above, here’s your chance to make your case.

The main ex­hibits will be color and com­pu­ta­tion. Then we’ll talk about refer­ence; then time; and fi­nally the “unity of con­scious­ness”.

Color was an is­sue last time. I ended up go­ing back and forth fruitlessly with sev­eral peo­ple. From my per­spec­tive it’s very sim­ple: where is the color in your the­ory? Whether your physics con­sists of fields and par­ti­cles in space, or flows of am­pli­tude in con­figu­ra­tion space, or even if you think re­al­ity con­sists of “math­e­mat­i­cal struc­tures” or Pla­tonic com­puter pro­grams, or what­ever—I don’t see any­thing red or green there, and yet I do see it right now, here in re­al­ity. So if you in­tend to tell me that re­al­ity con­sists solely of physics, math­e­mat­ics, or com­pu­ta­tion, you need to tell me where the col­ors are.

Oc­ca­sion­ally some­one says that red and green are just words, and they don’t even mean the same thing for differ­ent cul­tures or differ­ent peo­ple. True. But that’s just a mat­ter of clas­sifi­ca­tion. It’s a fact that the in­di­vi­d­ual shades of color ex­ist, how­ever it is that we group them—and your on­tol­ogy must con­tain them, if it pre­tends to com­plete­ness.

Then, there are var­i­ous other things which have some re­la­tion to color—the physics of sur­face re­flec­tion, or the cog­ni­tive neu­ro­science of color at­tri­bu­tion. I think we all agree that the first doesn’t mat­ter too much; you don’t even need blue light to see blue, you just need the right nerves to fire. So the sec­ond one seems a lot more rele­vant, in the at­tempt to ex­plain color us­ing the physics we have. Some­how the an­swer lies in the brain.

There is one last dodge com­pa­rable to fo­cus­ing on color words, namely, fo­cus­ing on color-re­lated cog­ni­tion. Ex­plain­ing why you say the words, ex­plain­ing why you cat­e­go­rize the per­ceived ob­ject as be­ing of a cer­tain color. We’re get­ting closer here. The ex­pla­na­tion of color, if there is such, clearly has a close con­nec­tion to those ex­pla­na­tions.

But in the end, ei­ther you say that blue­ness is there, or it is not there. And if it is there, at least “in ex­pe­rience” or “in con­scious­ness”, then some­thing some­where is blue. And all there is in the brain, ac­cord­ing to stan­dard physics, is a bunch of par­ti­cles in var­i­ous chang­ing con­figu­ra­tions. So: where’s the blue? What is the blue thing?

I can’t an­swer that ques­tion. At least, I can’t an­swer that ques­tion for you if you hold with or­tho­doxy here. How­ever, I have no­ticed maybe three or­tho­dox ap­proaches to this ques­tion.

First is faith. I don’t un­der­stand how it could be so, but I’m sure one day it will make sense.

Se­cond, puz­zle­ment plus faith. I don’t un­der­stand how it could be so, and I agree that it re­ally re­ally looks like an in­sur­mountable prob­lem, but we over­came great prob­lems in the past with­out hav­ing to over­throw the whole of sci­ence. So maybe if we stand on our heads, hold our breath, and think differ­ent, one day it will all make sense.

Third, du­al­ism that doesn’t no­tice it’s du­al­ism. This comes from peo­ple who think they have an an­swer. The blue­ness is the pat­tern of neu­ral firing, or the von Neu­mann en­tropy of the neu­ral state com­pared to that of the light source, or some other par­tic­u­lar phys­i­cal en­tity or prop­erty. If one then asks, okay, if you say so, but where’s the blue… the re­ac­tions vary. But a com­mon theme seems to be that blue­ness is a “feel” some­how “as­so­ci­ated” with the en­tity, or even as­so­ci­ated with be­ing the en­tity. To see blue is how it feels to have your neu­rons firing that way.

This is the du­al­ism which doesn’t know it’s du­al­ism. We have a perfectly sen­si­ble and pre­cise phys­i­cal de­scrip­tion of neu­rons firing: ions mov­ing through macro­molec­u­lar gate­ways in a mem­brane, and so forth. There’s no end of things we can say about it. We can count the num­ber of ions in a par­tic­u­lar spa­tial vol­ume, we can de­scribe how the elec­tro­mag­netic fields de­velop, we can say that this was caused by that… But you’ll no­tice—noth­ing about feels. When you say that this feels like some­thing, you’re in­tro­duc­ing a whole new prop­erty to the phys­i­cal de­scrip­tion. Ba­si­cally, you’re con­struct­ing a dual-as­pect ma­te­ri­al­ism, just like David Chalmers pro­posed. Tech­ni­cally, you’re a prop­erty du­al­ist rather than a sub­stance du­al­ist.

Now du­al­ism is sup­posed to be be­yond hor­rible, so what’s the al­ter­na­tive? You can do a Den­nett and deny that any­thing is re­ally blue. A few peo­ple go there, but not many. If the blue­ness does ex­ist, and you don’t want to be a du­al­ist, and you want to be­lieve in ex­ist­ing physics, then you have to con­clude that blue­ness is what the physics was about all along. We rep­re­sented it to our­selves as be­ing about lit­tle point-par­ti­cles mov­ing around in space, but all we ever ac­tu­ally had was math­e­mat­ics and cor­rect pre­dic­tions, so it must be that some part of the math­e­mat­ics was ac­tu­ally talk­ing about blue­ness—real blue­ness—all along. Prob­lem solved!

Ex­cept, it’s rather hard to make this work in de­tail. Blue­ness, af­ter all, does not ex­ist in a vac­uum. It’s part of a larger ex­pe­rience. So if you take this path, you may as well say that ex­pe­riences are real, and part of physics must have been de­scribing them all along. And when you try to make some part of physics look like a whole ex­pe­rience—well, I won’t say the m word here. Still, this is the path I took, so it’s the one I en­dorse; it just leads you a lot fur­ther afield than you might imag­ine.

Next up, com­pu­ta­tion. Again, the ba­sic crit­i­cism is sim­ple, it’s the at­tempt to ra­tio­nal­ize things which makes the dis­cus­sion com­pli­cated. Peo­ple like to at­tribute com­pu­ta­tional states, not just to com­put­ers, but to the brain. And they want to say that thoughts, per­cep­tions, etc., con­sist of be­ing in a cer­tain com­pu­ta­tional state. But a phys­i­cal state does not cor­re­spond in­her­ently to any one com­pu­ta­tional state.

There’s also a prob­lem with se­man­tics—say­ing that the state is about some­thing—which I will come to in due course. But first up, let’s just look at the prob­lems in­volved in at­tribut­ing a non-refer­en­tial “com­pu­ta­tional state” to a phys­i­cal en­tity.

Phys­i­cally speak­ing, an ob­ject, like a com­puter or a brain, can be in any of a large num­ber of ex­act micro­phys­i­cal states. When we say it is in a com­pu­ta­tional state, we are group­ing those micro­phys­i­cally dis­tinct states to­gether and say­ing, ev­ery state in this group cor­re­sponds to the same ab­stract high-level state, ev­ery micro­phys­i­cal state in this other group cor­re­sponds to some other ab­stract high-level state, and so on. But there are many many ways of group­ing the states to­gether. Which clus­ter­ing is the true one, the one that cor­re­sponds to cog­ni­tive states? Re­mem­ber, the or­tho­doxy is func­tion­al­ism: low-level de­tails don’t mat­ter. To be in a par­tic­u­lar cog­ni­tive state is to be in a par­tic­u­lar com­pu­ta­tional state. But if the “com­pu­ta­tional state” of a phys­i­cal ob­ject is an ob­server-de­pen­dent at­tri­bu­tion rather than an in­trin­sic prop­erty, then how can my thoughts be brain states?

We didn’t have this dis­cus­sion be­fore, so I won’t try to an­ti­ci­pate the pos­si­ble defenses of func­tion­al­ism. No-one will be sur­prised, I sup­pose, to hear that I don’t be­lieve this ei­ther. In­stead, I de­duce from this prob­lem that func­tion­al­ism is wrong. But here’s your chance, func­tion­al­ists: tell the world the one true state-clus­ter­ing which tells us the com­pu­ta­tion be­ing im­ple­mented by a phys­i­cal ob­ject!

I promised a prob­lem with se­man­tics too. Again I think it’s pretty sim­ple. Even if we set­tle on the One True Clus­ter­ing of microstates—each such macrostate is still just a re­gion of a phys­i­cal con­figu­ra­tion space. Thoughts have se­man­tic con­tent, they are “about” things. Where’s the about­ness?

I also promised to men­tion time and unity-of-con­scious­ness in con­clu­sion. Time I think offers an­other out­stand­ing ex­am­ple of the will to deny an as­pect of con­scious ex­pe­rience (or rather, to call it an illu­sion) for the sake of in­sist­ing that re­al­ity con­forms en­tirely to a par­tic­u­lar sci­en­tific on­tol­ogy. Ba­si­cally, we have a physics that spa­tial­izes time; we can vi­su­al­ize a space-time as a static, com­pleted thing. So time in the sense of flow—change, pro­cess—isn’t there in the model; but it ap­pears to be there in re­al­ity; there­fore it is an illu­sion.

Without try­ing to pre­empt the de­bate about time, per­haps you can see by now why I would be rather skep­ti­cal of at­tempts to deny the ob­vi­ous for the sake of a par­tic­u­lar sci­en­tific on­tol­ogy. Per­haps it’s not ac­tu­ally nec­es­sary. Maybe, if some­one thinks about it hard enough, they can come up with an on­tol­ogy in which time is real and “flows” af­ter all, and which still gives rise to the right phys­i­cal pre­dic­tions. (In gen­eral rel­a­tivity, a world-line has a lo­cal time as­so­ci­ated with it. So if the world-line is that of an ac­tu­ally and per­sis­tently ex­ist­ing ob­ject, per­haps time can be real and flow­ing in­side the ob­ject… in some sense. That’s my sug­ges­tion.)

And fi­nally, unity of con­scious­ness. In the de­bate over phys­i­cal­ism and con­scious­ness, the dis­cus­sion usu­ally doesn’t even get this far. It gets stuck on whether the in­di­vi­d­ual “qualia” are real. But they do ac­tu­ally form a whole. All this stuff—color, mean­ing, time—is drawn from that whole. It is a real and very difficult task to prop­erly char­ac­ter­ize that whole: not just what its in­gre­di­ents are, but how they are joined to­gether, what it is that makes it a whole. After all, that whole is your life. Nonethe­less, if any­one has come this far with me, per­haps you’ll agree that it’s the on­tol­ogy of the sub­jec­tive whole which is the ul­ti­mate challenge here. If we are go­ing to say that a par­tic­u­lar on­tol­ogy is the way that re­al­ity is, then it must not only con­tain color, mean­ing, and time, it has to con­tain that sub­jec­tive whole. In phe­nomenol­ogy, the stan­dard term for that whole is the “life­world”. Even cranky mis­taken re­duc­tion­ists have a life­world—they just haven’t no­ticed the in­con­sis­ten­cies be­tween what they be­lieve and what they ex­pe­rience. The ul­ti­mate challenge in the sci­ence of con­scious­ness is to get the on­tol­ogy of the life­world right, and then to find a broader sci­en­tific on­tol­ogy which con­tains the life­world on­tol­ogy. But first, as difficult as it may seem, we have to get past the par­tial on­tolo­gies which, for all their pre­dic­tive power and their se­duc­tive ex­act­ness, just can’t be the whole story.