I Might be a Brain in a Vat

But I like my senses, so I’ll roll with them

I’m David Abbott, and I’m a primate. My ancestors include chemists, architects, farmers, Neanderthals, proto-chordates and unicellular organisms. Every one of them successfully reproduced.

For 190,000 years, my forbearers were hunter gatherers in Africa and Europe. I haven’t met them, but my brain is a lot like theirs. It has evolved to kill large herbivores and use their flesh to seduce young women. Strangely, I’ve never hunted or even eaten meat. My mother raised me as a vegetarian, and that stuck. I do like women and have bought meat for them.

This isn’t really a blog about philosophy and evolutionary psychology, though both interest me. It is a blog about politics and economics and daily life written by a dude who believes that the world is entirely physical, that free will is an illusion and that all historical events were inevitable. Many of my posts will make no or only passing reference to my philosophical and psychological beliefs. Yet my views on politics intertwine with my understanding of human nature. When I talk to friends or comment on other substacks, we often talk past each other. It’s hard to discuss criminal justice with someone who blames criminals for making bad choices when no organism in the history of the universe has ever made a choice, good, bad, or otherwise. Those who believe in free will can badly overestimate the malleability of human nature and obsess about how people “should act,” rather than trying to predict how they will act. I seek policies that strongly correlate with outcomes I want. I don’t dwell on causation, because it requires reference to counterfactual worlds. There are arbitrarily many counterfactual worlds, so the whole thing is just a stupid parlor game. I want actions that perfectly correlate with my desired outcomes, but I’ll settle for the best r-squared I can find. When I said earlier that smallish numbers of electrons in brains have “big effects,” I meant that their behavior correlates tightly with different human-scale actions. It’s correlation all the way down!

I must have become a determinist sometime during college, but I forget exactly when. I studied philosophy much like a young Christian studies the Bible. Parliamentary debate was my pulpit. At eighteen, I wanted to know what was right, do what was right, profess philosophy, evangelize for truth and win acclaim for my rectitude. It didn’t work out and people rarely found me that righteous.

At twenty, I had no answer to the naturalistic fallacy. I was fully convinced that I existed, Descartes was persuasive on that point. I was willing to assume that I wasn’t a brain in a vat or, that if I were, it didn’t matter because I couldn’t see the vat or the dudes trying to trick me into thinking I was a philosophy student. Life would be more coherent if I acted like the world were real, so I did. That assumption has kept me out of mental hospitals. I’m cool with assuming the world is real and I won’t demand the receipts.

By twenty-one, I was a nihilist. Not a Goth-style, drug-addled, tear-this-mother-fucker down nihilist, but rather a preppy, wine-drinking, there aren’t any objective values so let’s have fun and not kill ourselves too quickly sort of nihilist. That’s pretty much who I am today, though I drink less and play more pickleball than twenty years ago. Not killing yourself too quickly gets harder as you age.

The world that I happily assume is real is entirely physical. The only truth is the location and vector of every particle. The problem is this is trillions of times more truth than any human brain can handle. It’s trillions of times more data than a supercomputer can process A single chromosome in a single cell is vastly more complicated than a chessboard. A supercomputer can analyze all viable lines in a chess game about twenty moves ahead, but would founder trying to describe the locations and vectors of the particles in a single strand of DNA over the course of a single second.

To understand human environments, we must use far bigger units than protons, neutrons and electrons. A pint of milk, a pound of meat, a beautiful face and a sharp stone are the natural scale of human interest and action. A trillion electrons are generally no big deal, unless they are in a brain.

Brains are special and devilishly hard to model because smallish numbers of particles can have big effects. The human brain is the most complex structure in the known universe with 100 trillion (100,000,000,000,000) neural connections. A computer that can see twenty moves ahead in a chess game could never model the thought of a single human at the molecular level. Even if it could capture the exquisite complexity of the brain, new connections are constantly being formed and old connections being severed. Even if the neural structure of the brain were completely stable, computers will never have the computational power to grind through the myriad interactions of every particle within the brain. Human action will always be veiled in mystery.

If we can’t describe thought at the molecular level, how can we know that thought is, fundamentally, molecular? First, it is extremely unlikely that the most complex structure in the known universe is a useless ornament. It took a lot of natural selection to produce it. If an immaterial homunculus is doing the actual deciding, why do our bodies invest precious protein, oxygen, and energy in our brains? Why would our ancestors squander their most vital resources on such foppery when malnutrition was common and starvation far from rare. Second, it’s clear that physical things like light, sound, alcohol and psychiatric drugs influence mental activity. Cut off a genius’s protein supply for long enough and his body will begin metabolizing his brain and making him dumb. Finally, computers are showing that purely physical objects that no one thinks have a soul or a homunculus can play chess, recognize language, and even write decent essays. The human brain is a really versatile but kind of slow computer.

We are flotsam and jetsam in a deterministic sea, our desires, though real and sometimes passionate, dictated by our genes and circumstances. No one is to blame for anything. Whatever happens was inevitable. Some people think this worldview is depressing. Why does anything matter if we can’t “change” it and it’s going to happen anyway?

Consider this thought experiment. The grand inquisitor has assembled an auto de fe. You, a heretic, are at grave risk of immolation. You don’t know your fate, only the grand inquisitor does. He’s written it in a sealed letter and handed it to the jailers. Does your fate matter? Does it matter any less because it has already been decided? Would your fate matter more if it were decided by a random number generator? By some momentary and ineffable caprice in the inquisitor’s brain? By some mysterious quantum-level event? Not really. Being burned alive sucks whether or not the inquisitor has free will and whether or not your execution is inevitable.

Say you want to avoid being executed. It would be far more useful to predict what kind of things get you burned and not do them than to opine on how the inquisitor should act or whether he has run afoul of the categorical imperative. Making good predictions can save your life.

This blog is the work of a primate who wants to be happy and enjoys arguing about politics. Our path into eternity is wrought of iron rails yet favors those who can see through the fog more clearly than others. I hope to clarify my own thoughts and maybe find a few clever materialists to engage.

Comments are welcome.