Thou Art Physics

Three months ago—jee­bers, has it re­ally been that long?—I posed the fol­low­ing home­work as­sign­ment: Do a stack trace of the hu­man cog­ni­tive al­gorithms that pro­duce de­bates about “free will.” Note that this task is strongly dis­t­in­guished from ar­gu­ing that free will does or does not ex­ist.

Now, as ex­pected, peo­ple are ask­ing, “If the fu­ture is de­ter­mined, how can our choices con­trol it?” The wise reader can guess that it all adds up to nor­mal­ity; but this leaves the ques­tion of how.

Peo­ple hear: “The uni­verse runs like clock­work; physics is de­ter­minis­tic; the fu­ture is fixed.” And their minds form a causal net­work that looks like this:

Here we see the causes “Me” and “Physics,” com­pet­ing to de­ter­mine the state of the “Fu­ture” effect. If the “Fu­ture” is fully de­ter­mined by “Physics,” then ob­vi­ously there is no room for it to be af­fected by “Me.”

This causal net­work is not an ex­plicit philo­soph­i­cal be­lief. It’s im­plicit— a back­ground rep­re­sen­ta­tion of the brain, con­trol­ling which philo­soph­i­cal ar­gu­ments seem “rea­son­able.” It just seems like the way things are.

Every now and then, an­other neu­ro­science press re­lease ap­pears, claiming that, be­cause re­searchers used an fMRI to spot the brain do­ing some­thing-or-other dur­ing a de­ci­sion pro­cess, it’s not you who chooses, it’s your brain.

Like­wise that old chest­nut, “Re­duc­tion­ism un­der­mines ra­tio­nal­ity it­self. Be­cause then, ev­ery time you said some­thing, it wouldn’t be the re­sult of rea­son­ing about the ev­i­dence—it would be merely quarks bop­ping around.”

Of course the ac­tual di­a­gram should be:

Or bet­ter yet:

Why is this not ob­vi­ous? Be­cause there are many lev­els of or­ga­ni­za­tion that sep­a­rate our mod­els of our thoughts—our emo­tions, our be­liefs, our ag­o­niz­ing in­de­ci­sions, and our fi­nal choices—from our mod­els of elec­trons and quarks.

We can in­tu­itively vi­su­al­ize that a hand is made of fingers (and thumb and palm). To ask whether it’s re­ally our hand that picks some­thing up, or merely our fingers, thumb, and palm, is trans­par­ently a wrong ques­tion.

But the gap be­tween physics and cog­ni­tion can­not be crossed by di­rect vi­su­al­iza­tion. No one can vi­su­al­ize atoms mak­ing up a per­son, the way they can see fingers mak­ing up a hand.

And so it re­quires con­stant vigilance to main­tain your per­cep­tion of your­self as an en­tity within physics.

This vigilance is one of the great keys to philos­o­phy, like the Mind Pro­jec­tion Fal­lacy. You will re­call that it is this point which I nom­i­nated as hav­ing tripped up the quan­tum physi­cists who failed to imag­ine macro­scopic de­co­her­ence; they did not think to ap­ply the laws to them­selves.

Beliefs, de­sires, emo­tions, morals, goals, imag­i­na­tions, an­ti­ci­pa­tions, sen­sory per­cep­tions, fleet­ing wishes, ideals, temp­ta­tions… You might call this the “sur­face layer” of the mind, the parts-of-self that peo­ple can see even with­out sci­ence. If I say, “It is not you who de­ter­mines the fu­ture, it is your de­sires, plans, and ac­tions that de­ter­mine the fu­ture,” you can read­ily see the part-whole re­la­tions. It is im­me­di­ately visi­ble, like fingers mak­ing up a hand. There are other part-whole re­la­tions all the way down to physics, but they are not im­me­di­ately visi­ble.

“Com­pat­i­bil­ism” is the philo­soph­i­cal po­si­tion that “free will” can be in­tu­itively and satis­fy­ingly defined in such a way as to be com­pat­i­ble with de­ter­minis­tic physics. “In­com­pat­i­bil­ism” is the po­si­tion that free will and de­ter­minism are in­com­pat­i­ble.

My po­si­tion might per­haps be called “Re­quire­dism.” When agency, choice, con­trol, and moral re­spon­si­bil­ity are cashed out in a sen­si­ble way, they re­quire de­ter­minism—at least some patches of de­ter­minism within the uni­verse. If you choose, and plan, and act, and bring some fu­ture into be­ing, in ac­cor­dance with your de­sire, then all this re­quires a lawful sort of re­al­ity; you can­not do it amid ut­ter chaos. There must be or­der over at least those parts of re­al­ity that are be­ing con­trol­led by you. You are within physics, and so you/​physics have de­ter­mined the fu­ture. If it were not de­ter­mined by physics, it could not be de­ter­mined by you.

Or per­haps I should say, “If the fu­ture were not de­ter­mined by re­al­ity, it could not be de­ter­mined by you,” or “If the fu­ture were not de­ter­mined by some­thing, it could not be de­ter­mined by you.” You don’t need neu­ro­science or physics to push naive defi­ni­tions of free will into in­co­her­ence. If the mind were not em­bod­ied in the brain, it would be em­bod­ied in some­thing else; there would be some real thing that was a mind. If the fu­ture were not de­ter­mined by physics, it would be de­ter­mined by some­thing, some law, some or­der, some grand re­al­ity that in­cluded you within it.

But if the laws of physics con­trol us, then how can we be said to con­trol our­selves?

Turn it around: If the laws of physics did not con­trol us, how could we pos­si­bly con­trol our­selves?

How could thoughts judge other thoughts, how could emo­tions con­flict with each other, how could one course of ac­tion ap­pear best, how could we pass from un­cer­tainty to cer­tainty about our own plans, in the midst of ut­ter chaos?

If we were not in re­al­ity, where could we be?

The fu­ture is de­ter­mined by physics. What kind of physics? The kind of physics that in­cludes the ac­tions of hu­man be­ings.

Peo­ple’s choices are de­ter­mined by physics. What kind of physics? The kind of physics that in­cludes weigh­ing de­ci­sions, con­sid­er­ing pos­si­ble out­comes, judg­ing them, be­ing tempted, fol­low­ing morals, ra­tio­nal­iz­ing trans­gres­sions, try­ing to do bet­ter…

There is no point where a quark swoops in from Pluto and over­rides all this.

The thoughts of your de­ci­sion pro­cess are all real, they are all some­thing. But a thought is too big and com­pli­cated to be an atom. So thoughts are made of smaller things, and our name for the stuff that stuff is made of is “physics.”

Physics un­der­lies our de­ci­sions and in­cludes our de­ci­sions. It does not ex­plain them away.

Re­mem­ber, physics adds up to nor­mal­ity; it’s your cog­ni­tive al­gorithms that gen­er­ate con­fu­sion.