Fundamental Doubts

Fol­lowup to: The Ge­netic Fal­lacy, Where Re­cur­sive Jus­tifi­ca­tion Hits Bottom

Yes­ter­day I said that—be­cause hu­mans are not perfect Bayesi­ans—the ge­netic fal­lacy is not en­tirely a fal­lacy; when new sus­pi­cion is cast on one of your fun­da­men­tal sources, you re­ally should doubt all the branches and leaves of that root, even if they seem to have ac­cu­mu­lated new ev­i­dence in the mean­while.

This is one of the most difficult tech­niques of ra­tio­nal­ity (on which I will sep­a­rately post, one of these days). Descartes, set­ting out to “doubt, in­so­far as pos­si­ble, all things”, ended up try­ing to prove the ex­is­tence of God—which, if he wasn’t a se­cret athe­ist try­ing to avoid get­ting burned at the stake, is pretty pa­thetic. It is hard to doubt an idea to which we are deeply at­tached; our mind nat­u­rally reaches for cached thoughts and re­hearsed ar­gu­ments.

But to­day’s post con­cerns a differ­ent kind of difficulty—the case where the doubt is so deep, of a source so fun­da­men­tal, that you can’t make a true fresh be­gin­ning.

Case in point: Re­mem­ber when, in the The Ma­trix, Mor­pheus told Neo that the ma­chines were har­vest­ing the body heat of hu­mans for en­ergy, and liquefy­ing the dead to feed to ba­bies? I sup­pose you thought some­thing like, “Hey! That vi­o­lates the sec­ond law of ther­mo­dy­nam­ics.”

Well, it does vi­o­late the sec­ond law of ther­mo­dy­nam­ics. But if the Ma­trix’s mak­ers had cared about the flaw once it was pointed out to them, they could have fixed the plot hole in any of the se­quels, in fif­teen sec­onds, this eas­ily:

Neo: “Doesn’t har­vest­ing hu­man body heat for en­ergy, vi­o­late the laws of ther­mo­dy­nam­ics?”

Mor­pheus: “Where’d you learn about ther­mo­dy­nam­ics, Neo?”

Neo: “In school.”

Mor­pheus: “Where’d you go to school, Neo?”

Neo: “Oh.”

Mor­pheus: “The ma­chines tell el­e­gant lies.”

Now, mind you, I am not say­ing that this ex­cuses the origi­nal mis­take in the script. When my mind gen­er­ated this ex­cuse, it came clearly la­beled with that warn­ing sign of which I have spo­ken, “Tada! Your mind can gen­er­ate an ex­cuse for any­thing!” You do not need to tell me that my plot-hole-patch is a nitwit idea, I am well aware of that...

...but, in point of fact, if you woke up out of a vir­tual re­al­ity pod one day, you would have to sus­pect all the physics you knew. Even if you looked down and saw that you had hands, you couldn’t rely on there be­ing blood and bone in­side them. Even if you looked up and saw stars, you couldn’t rely on their be­ing trillions of miles away. And even if you found your­self think­ing, you couldn’t rely on your head con­tain­ing a brain.

You could still try to doubt, even so. You could do your best to un­wind your thoughts past ev­ery les­son in school, ev­ery sci­ence pa­per read, ev­ery sen­sory ex­pe­rience, ev­ery math proof whose seem­ing ap­proval by other math­e­mat­i­ci­ans might have been chore­ographed to con­ceal a sub­tle flaw...

But sup­pose you dis­cov­ered that you were a com­puter pro­gram and that the Dark Lords of the Ma­trix were ac­tively tam­per­ing with your thoughts.

Well… in that sce­nario, you’re pretty much screwed, I’d have to say.

Descartes vastly un­der­es­ti­mated the pow­ers of an in­finitely pow­er­ful de­ceiv­ing de­mon when he sup­posed he could trust “I think there­fore I am.” Maybe that’s just what they want you to think. Maybe they just in­serted that con­clu­sion into your mind with a mem­ory of it seem­ing to have an ir­refutable chain of log­i­cal sup­port, along with some peer pres­sure to la­bel it “un­ques­tion­able” just like all your friends.

(Per­son­ally, I don’t trust “I think there­fore I am” even in real life, since it con­tains a term “am” whose mean­ing I find con­fus­ing, and I’ve learned to spread my con­fi­dence in­ter­vals very widely in the pres­ence of ba­sic con­fu­sion. As for ab­solute cer­tainty, don’t be silly.)

Every mem­ory of jus­tifi­ca­tion could be faked. Every feel­ing of sup­port could be ar­tifi­cially in­duced. Mo­dus po­nens could be a lie. Your con­cept of “ra­tio­nal jus­tifi­ca­tion”—not just your spe­cific con­cept, but your no­tion that any such thing ex­ists at all—could have been man­u­fac­tured to mis­lead you. Your trust in Rea­son it­self could have been in­cul­cated to throw you off the trail.

So you might as well not think about the pos­si­bil­ity that you’re a brain with chore­ographed thoughts, be­cause there’s noth­ing you can do about it...

Un­less, of course, that’s what they want you to think.

Past a cer­tain level of doubt, it’s not pos­si­ble to start over fresh. There’s noth­ing you can unas­sume to find some firm rock on which to stand. You can­not un­wind your­self into a perfectly empty and perfectly re­li­able ghost in the ma­chine.

This level of meta-sus­pi­cion should be a rare oc­ca­sion. For ex­am­ple, sus­pect­ing that all aca­demic sci­ence is an or­ga­nized con­spir­acy, should not run into any­thing like these meta-difficul­ties. Cer­tainly, some­one does not get to plead that un­wind­ing past the Bible is im­pos­si­ble be­cause it is too foun­da­tional; athe­ists walk the Earth with­out fal­ling into co­mas. Re­mem­ber, when Descartes tried to out­wit an in­finitely pow­er­ful de­ceiv­ing de­mon, he first tried to make him­self ab­solutely cer­tain of a highly con­fus­ing state­ment, and then proved the ex­is­tence of God. Con­sider that a cau­tion about what you try to claim is “too ba­sic for a fresh be­gin­ning”. And even ba­sic things can still be doubted, it is only that we use our un­trust­wor­thy brains to doubt them.

Or con­sider the case of our ex­is­tence as evolved brains. Nat­u­ral se­lec­tion isn’t trust­wor­thy, and we have spe­cific rea­son to sus­pect it. We know that evolu­tion is stupid. We know many spe­cific ways in which our hu­man brains fail, taken be­yond the sa­vanna. But you can’t clear your mind of evolu­tion­ary in­fluences and start over. It would be like de­cid­ing that you don’t trust neu­rons, so you’re go­ing to clear your mind of brains.

And evolu­tion cer­tainly gets a chance to in­fluence ev­ery sin­gle thought that runs through your mind! It is the very rea­son why you ex­ist as a thinker, rather than a lump of car­bon—and that doesn’t mean evolu­tion sum­moned a ghost-in-the-ma­chine into you; it de­signed the ghost. If you learn cul­ture, it is be­cause you were built to learn cul­ture.

But in fact, we don’t run into un­man­age­able meta-trou­ble in try­ing to come up with spe­cific patches for spe­cific known evolved bi­ases. And evolu­tion is stupid, so even though it has set up self-de­cep­tive cir­cuits in us, these cir­cuits are not in­finitely difficult to com­pre­hend and out­wit.

Or so it seems! But it re­ally does seem that way, on re­flec­tion.

There is no but­ton you can press to rewind past your noisy brain, and be­come a perfectly re­li­able ghost of perfect empti­ness. That’s not just be­cause your brain is you. It’s also be­cause you can’t unas­sume things like modus po­nens or be­lief up­dat­ing. You can unas­sume them as ex­plicit premises for de­liber­ate rea­son­ing—a hunter-gath­erer has no ex­plicit con­cept of modus po­nens—but you can’t delete the ac­tual dy­nam­ics (and all their prod­ucts!)

So, in the end, I think we must al­low the use of brains to think about think­ing; and the use of evolved brains to think about evolu­tion; and the use of in­duc­tive brains to think about in­duc­tion; and the use of brains with an Oc­cam prior to think about whether the uni­verse ap­pears to be sim­ple; for these things we re­ally can­not un­wind en­tirely, even when we have rea­son to dis­trust them. Strange loops through the meta level, I think, are not the same as cir­cu­lar logic.

Part of The Me­taethics Sequence

Next post: “Re­bel­ling Within Na­ture

Pre­vi­ous post: “My Kind of Reflec­tion