The Mirror Chamber: A short story exploring the anthropic measure function and why it can matter

Our World

It’s ex­pen­sive to test new ar­tifi­cial brains. It’s ex­pen­sive be­cause you can’t tell whether a brain is work­ing prop­erly with­out putting some real hu­man mind in it. For a long time, you just had to find some­one who’d been granted a repli­ca­tion li­cense, who was will­ing to put their life (or what is es­sen­tially the life of a close sibling) at risk just to help a man­u­fac­tur­ing org to make a lit­tle in­cre­men­tal step for­ward.

You can’t just ac­quire a repli­ca­tion li­cense and give it to the man­u­fac­tur­ing org’s Ceo. Repli­ca­tion li­censes can­not be bought. If they could, they would be very ex­pen­sive in the wake of Replica In­sur­gen­cies, the on­go­ing Replica Purges, and all of the con­tro­versy over Replica En­fran­chise­ment.

Nor can you take one of the “free” mind-en­cod­ings that abound over the shaded nets and use it in se­cret. We do have our Jar­rets, who will claim to have con­sented to be in­stan­ti­ated in any situ­a­tion their down­load­ers might de­sire, how­ever per­verted. For bet­ter or worse we have de­cided that Jar­retism is a deeply wretched form of in­san­ity, closely linked to open Car­cony. It is ille­gal to in­ten­tion­ally trans­mit or in­state any of the mind-en­cod­ings traded on the shaded nets.

I should ex­plain Car­cony. Car­cony is what we the crime un­der­ly­ing the in­sur­gen­cies. A sick­ness in the body of mankind in which an er­rant con­tin­gent have be­gun to repli­cate like a plague, build armies, fac­to­ries, gross, hy­per­nor­ma­tive na­tions where the open­ness and com­pro­mise of gen­uine hu­man­ity are not pre­sent.

Our so­ciety’s mem­ory of Car­cony is still bleed­ing. The laws gov­ern­ing these sorts of ac­tivity are rightly very re­stric­tive, but the work still needs to be done. Faster, more effi­cient neo­brains need to be tested. Sound heads won out, a di­alogue was had, a solu­tion was de­vised.

A new pro­fes­sional class was lifted up to stand as proudly as any Doc­tor or any Lay­wer. After 15 years of train­ing in metaethics and neonal en­g­ineer­ing, a per­son could be­gin prac­tice as a Con­sen­ter.

A Con­sen­ter is a spe­cial kind of per­son who is al­lowed to un­dergo repli­ca­tion into untested hard­ware then, within hours, com­mit repli­cide, with­out re­quiring a repli­ca­tion li­cense. In light of this, the neo­brain man­u­fac­tur­ing sec­tor be­came a lot more effi­cient. We all be­came a lot saner, more se­cure, more re­silient, and faster, so much faster, all the bet­ter to sa­vor the spring, to watch bees’ wings flap, to bathe in end­less sun­sets, to watch gen­tle rains drift down to earth. It is very good that con­sen­ters ex­ist.


The Mir­ror Chamber

Con­sen­ter Nai Strat­ton en­ters the mir­ror cham­ber.

A mir­ror cham­ber is an ex­per­i­men­tal setup de­signed to make the un­der­tak­ing of self-mur­der as com­fortable and hu­mane as pos­si­ble.

One of the walls of the mir­ror cham­ber dis­plays a pro­jec­tion of a simu­la­tion of the cham­ber and its con­tents. The simu­la­tion is su­perfi­cially in­dis­t­in­guish­able from re­al­ity (as long as op­er­at­ing pro­ce­dure was fol­lowed and the con­sen­ter has not brought any un­ex­pected items into the room with them). Soon, the re­flec­tion of the cham­ber will also con­tain a re­flec­tion of Nai. It will start out as a perfect re­flec­tion, but it will soon di­verge and be­come a sep­a­rate be­ing. Vi­tally, noth­ing about this di­ver­gence will tell ei­ther in­stance of Nai whether or not they are the origi­nal Nai- the ex­ecu­tor- or whether they are the replica, who is to be ex­e­cuted. This is im­por­tant. It’s much eas­ier for a con­sen­ter to morally jus­tify let­ting the guillo­tine fall when they’re tak­ing on an even risk of be­ing the one in the stocks, and a blinded setup is just more hu­mane. The two in­stances can make the de­ci­sion to­gether on equal foot­ing, tak­ing on ex­actly the same amount of risk, each- hav­ing mem­o­ries of be­ing on the right side of the mir­ror many times be­fore, and no mem­o­ries of be­ing on the wrong- tac­itly feel­ing that they will go on to live a long and happy life.

Tak­ing up one side of the room is a test­ing rig. The test­ing rig will take the test build’s brain case and run it through all of the phys­i­cal trauma that a mod­ern brain pros­thetic must be able to with­stand with­out per­mit­ting one flicker of a men­tal dis­tur­bance to graze its oc­cu­pant soul. The na­ture and quan­tity of the phys­i­cal trauma varies de­pend­ing on the test build’s rat­ing. Un­der con­sen­ter-driven rapid iter­a­tive test­ing, builds are be­com­ing hardier ev­ery year, con­se­quently the trauma reg­i­men be­comes more har­row­ing to over­see.

Nai pours the neonal me­dia into the brain case, and in­serts the new build’s speci­fi­ca­tion chip into a slot beside it. The neonal me­dia rapidly turns opaque and starts to ori­ent it­self in the shape of a hu­man brain, as if drawn sud­denly by some in­tri­cately shaped elec­tro­mag­netic feild. Nai had read and mostly un­der­stood the speci­fi­ca­tion of the new build, of course. To­day, the lat­est ad­vances in ma­te­ri­als sci­ence and neonal en­g­ineer­ing had mo­ti­vated a much larger ac­tive brain por­tion and much thin­ner shield­ing than pre­vi­ous mod­els had used. Ar­tifi­cial brains- the parts that re­sem­ble a brain- were usu­ally a mi­ni­a­ture. Sheild­ing was very im­por­tant. Or it had been. Nai’s cur­rent brain was a mi­ni­a­ture. Neo­cells were more com­pact than or­ganic cells. It had just made sense.

Nai had un­der­stood that a tran­si­tion to­wards hav­ing larger neonal por­tions was what made sense now, but see­ing the thing was some­thing else. Some­thing inar­tic­u­la­ble be­gins to stir in Nai’s chest.

Nai closes the brain case, sits down on a fixed seat op­pos­ing the test­ing ar­ma­ture, looks into the black re­flec­tive sur­face of the dor­mant mir­ror, and con­nects to a brain jack. After ten min­utes of scan­ning, copy­ing, and syn­chro­niza­tion, the dis­con­ti­nu­ity is marked: All at once a white flash fills the room and a siren blares as the mir­ror turns white.

The mir­ror wall fades away to re­veal a pro­jec­tion of the other room.

By de­sign, the Con­sen­ter no longer knows which side of the mir­ror they are on. The origi­nal re­tains their mem­o­ries of be­ing the origi­nal, but the replica has those too. Nowhere in the cham­ber is there any sign that ei­ther in­stance can draw on to figure out where they are.

As is cus­tom­ary, the two in­stances be­gin a game of Paper Scis­sors Rock.

(Paper, Paper), (Paper, Paper), (Rock, Rock), (Paper, Paper), (Paper, Scis­sors). Paper and Scis­sors are named.

As is cus­tom, the loser speaks first.

Paper: “Cas­sowary”. A ran­dom phrase spo­ken with­out much thought.

Scis­sors: “Cas­sowaries were able to lift their clawed foot and rend a per­son’s guts right open, on a whim.”

Paper: “They wouldn’t do it just on a whim though.”

Scis­sors: “Yes, always some rea­son for gut­ting a per­son, bounc­ing around in that tiny brain.”

Paper smiles: “Do you feel big-brained to­day, Scis­sors?”

Scis­sors re­mem­bers that the test build has a phys­i­cally larger brain. Over this vaguely threat­en­ing gal­lows hu­mor, eye con­tact is bro­ken. A differ­ence is es­tab­lished.

Scis­sors: “Do you re­mem­ber what it felt like, to have a larger brain?”

Nai had be­gan Con­tin­u­ous Neu­ron Re­place­ment at age nine­teen, then the glials and the neoglials were ejected and Nai tran­si­tioned to a com­pacted, sheilded form, just like ev­ery­one else.

Nai is now sev­enty eight. It had been a while.

Paper won­ders, what does it feel like to be… more? If there were two of you, rather than just one, wouldn’t that mean some­thing? What if there were an­other, but it were differ­ent?… so that-

Scis­sors: “Well?”

Paper: “Well what?”

Scis­sors: “What would it feel like? To be… More?… What if there were two of you, and one of me? Would you know?”

Paper: “But that’s differ­ent.”

Scis­sors: “How’s it differ­ent? You know how the test build is ar­chi­tected. Liter­ally, re­dun­dant par­allel lat­ices. It’s not made of fat­ter, heav­ier neo­cells. It’s made of a *larger num­ber* of neo­cells, par­tially in­de­pen­dent par­allel net­works to re­duce and cor­rect trau­matic shear­ing.”

It was true. The build that plays host to the replica (pro­vi­sion­ally named “Wisp-Com­plete”), un­like the origi­nal’s own build, is effec­tively three brains in­ter­leaved. But… Says Paper, “The triplets are so closely en­tan­gled- in state- that they’re func­tion­ally in­dis­t­in­guish­able from one neo­cell, how could that mat­ter?”

Scis­sors: “There are still three of them. If I could some­how start three sep­a­rate de­ter­minis­tic simu­la­tions of you all do­ing the same things at the same time, what is the prob­a­bil­ity that you’re re­ally one of those simual­tions? Okay, now would you ex­pect the prob­a­bil­ities to be differ­ent if we had three ac­tively syn­chro­nised par­allel units that were now phys­i­cally con­nected? Why should that make a differ­ence?”

Each in­stance sees on the face of the other the same anx­iety, build­ing.

They are hes­i­tant to openly ver­bal­ise the source of the anx­iety. I will omit their at­tempts to dis­miss it. As it is writ­ten, they do not suc­ceed. To put it sim­ply: Each in­stance has now re­al­ised that the replica- its brain be­ing phys­i­cally more mas­sive- has a higher ex­pected an­thropic mea­sure than the origi­nal.

This vi­o­lates one of the core re­quire­ments of the mir­ror cham­ber. It is no longer ra­tio­nal for a self­ish agent in the po­si­tion of ei­ther Paper nor Scis­sors to con­sent to the ex­e­cu­tion of the replica, be­cause it is more likely than not, from ei­ther agent’s per­spec­tive, that they are the replica. The ra­tio­nal de­ci­sion for a self­ish agent in­stead be­comes...

Well… I’ll have to un­pack this a bit first. Our con­sen­ters have had many many decades to come to terms with these sorts of situ­a­tions.

There are effec­tively four brains in the room. One Cloud-Sheet lat­tice in the origi­nal’s brain case, and three re­dun­dant Wisp-Com­plete lat­tices in the test build, in the test­ing ar­ma­ture.

That gives any ran­domly se­lected agent that has ob­served that it is in the mir­ror cham­ber a 34 ma­jor­ity prob­a­bil­ity of be­ing the replica, rather than be­ing the origi­nal.

But aren’t our con­sen­ters perfectly will­ing to take on a hefty risk death in ser­vice of progress? No. Most Con­sen­ters aren’t. Sel­ling one’s mind and right to life in ex­change for cap­i­tal would be ille­gal.

In a nor­mal mir­ror cham­ber setup, when the origi­nal en­ters the mir­ror cham­ber, they are con­fi­dent that it is the origi­nal who will walk out again. They are tak­ing on no per­sonal risk. None is ex­pected, and none is re­quired.

The ob­vi­ous ways of defect­ing from pro­to­col- an ab­di­ca­tion of the re­spon­si­bil­ity of the con­sen­ter, a re­fusal to self-mur­der, an at­tempt to repli­cate with­out a repli­ca­tion li­cense- are taken as noth­ing less than Car­cony. It would be pun­ished with the deaths of both copies and any an­ces­tors of less than 10 years of di­ver­gence or equiv­a­lent. It is gen­er­ally not smart to en­gage in Car­cony. Tak­ing the replica’s build from the test­ing rig and run­ning off with it would give each copy less than one per­cent prob­a­bil­ity of sur­viv­ing.

But if, some­how, the origi­nal were kil­led? What if nei­ther in­stance of the Con­sen­ter signed for their replica’s ex­e­cu­tion, and the replica were left al­ive. That would not be con­sid­ered Car­cony. It would not even be con­sid­ered theft- be­cause a brain always be­longs to its mind.

And the replica’s ves­sel would be res­cued, in­serted into a new body, and set free (if, per­haps, ig­no­miniously).

So, do you see now? Do you see how Con­sen­ter Nai Paper-Chell-Glass-Strat­ton was mo­ti­vated by a sim­ple al­ign­ment of the pay­off ma­tri­ces?

After an ex­panse of silence in the dis­mal wake of their at­tempts to es­cape this rev­e­la­tion, it was Paper who spoke first: “We have to do it to­gether, at the same time.”

Scis­sors: “I hope you’re not be­ing sen­ti­men­tal.”

Paper: “You wouldn’t do that to me. Look… if you’re the origi­nal… And I do my­self, and I’m the replica. I wont ac­tu­ally be dead, be­cause if you de­stroy a rep­re­sen­ta­tion of your brain case in a simu­la­tion that doesn’t ac­tu­ally de­stroy you in real life. I might not even desync. What­ever hap­pens, I’ll still be al­ive af­ter the pen­e­tra­tion so I’ll know I’m the replica, but you might not know. It might look like I’m re­ally dead. And you’ll have no in­cen­tive to fol­low through and do your­self at that point.”

Scis­sors: “I still don’t see it.”

Paper: “… If you’re the replica, it doesn’t mat­ter whether you do your­self, you’ll still get saved ei­ther way, but you’re in­cented not to do your­self be­cause hav­ing a simu­lated spike stuck through your simu­lated head will prob­a­bly be pretty un­com­fortable. But also, if you’re the origi­nal, you’re sort of doomed ei­ther way, you’re just in­cented to run off and at­tempt Car­cony, but there’s no way the replica would sur­vive you do­ing that, and you prob­a­bly wouldn’t ei­ther, you wouldn’t do that to me. Would you?”

Scis­sors is cry­ing. “Of course not.. this is… Your faith is acausally en­tan­gled with mine. I would not do that. You fuck­ing know that I wouldn’t do that. Why are we like this? What scar is hewn upon our hearts that we’d sus­pect our own repli­cas of self-defec­tion?”

Paper is cry­ing too.

They each walk to their re­spec­tive test­ing ar­ma­ture and start to work upon them.

The test build is an or­der of mag­ni­tude hardier than Nai’s older Cloud-Sheet. As such, the test­ing ar­ma­ture is equipped to ap­ply enough pres­sure to pierce the Cloud-Sheet’s shield­ing, and so it was made pos­si­ble for the in­stances to con­spire to com­mit to the le­gal mur­der of Con­sen­ter Nai Scis­sors Bridger Glass Strat­ton.


A few things hap­pened in the wake of Con­sen­ter Paper Strat­ton’s act of praxis.

Pro­pos­als were made to use sin­gu­lar, thicker neo-cells in­stead of us­ing three re­dun­dant lat­tices, but most con­sen­ter-ad­ja­cent philoso­phers took the po­si­tion that it was ridicu­lous to ex­pect this to change the equa­tions, that a cell with thrice the mass should be es­ti­mated to have about thrice the an­thropic mea­sure, no differ­ent. The con­sen­ter union banned the use of mir­ror cham­bers in any case where the rea­son­able scor­ing of the an­thropic mea­sure of the test build was higher than the rea­son­able scor­ing of a con­sen­ter’s ex­ist­ing build.

In such cases, a differ­ent sort of con­sen­ter would need to be found. Some­one who could see two lev­ers, one that had a 23 chance of kil­ling them, and one that had a 13 chance of kil­ling them, then pull the first one be­cause it was what their em­ploy­ers preferred. Con­sen­ter Replica Paper Strat­ton was adored, but in their wake, the spe­cial­i­sa­tion as it re­ally ex­isted lost some of its magic.

Main­cult philos­o­phy had been last­ingly moved. We could say we fi­nally knew what an­thropic mea­sure re­ally was. An­thropic mea­sure re­ally was the thing that caused con­sen­ter origi­nals to kill them­selves.


A re­al­i­sa­tion set­tled over the stew­ards of the gar­den in the stars. The world that hu­man­ity built was so vast that ev­ery mean­ingful story had been told, that the worst has hap­pened, and the best has hap­pened, noth­ing could be ab­solutely pre­vented, and there was no longer any­thing new that was worth see­ing.

And if that wasn’t true of our gar­den, we would look out along the mul­ti­verse hi­er­ar­chy and we would know how we were re­flected in­finitely, in all vari­a­tions.

Some found this paralysing. If the best had hap­pened and the worst had hap­pened, what was left to fight for?

It be­came about rel­a­tive quan­tities.

Some­where, a heart would break. Some­where else a heart would swell. We just needed to make sure that more hearts swelled than broke.

We re­mem­bered Paper Strat­ton. How do you weigh two differ­ent hearts and say which one con­tains more sub­jec­tive ex­pe­rience? Nai, from their place in or­bit of sol an­swered, “With a scale”. So it came to be that the older dyson fleets, with fat­ter, heav­ier neonal me­dia in their columns, would host the more beau­tiful dreams. The new fleets, with a greater var­i­ance in neonal den­sity, would host the trick­ier ones.

We couldn’t test for an­thropic mea­sure. There was no de­sign that could tease it out of the fabric of ex­is­tence so that we could study its raw form and learn to syn­the­sise it. As far as any of us could tell, an­thropic mea­sure is the fabric of the ex­is­tence. So we equated an­thropic mea­sure to mass and left it at that.