Bayesian Rationality

“So we’ve established, as a baseline, that a correct application of the scientific method means we should assume that reality and consciousness are the same thing; the observer is the observed. Now let’s move on to some Bayesian rationality. Do you know what that is?”

“Nikki,” Zac sighed, “I’m a simple man with simple interests. Browsing 9Gag of a morning, making sure people on the internet know when they are wrong, occasionally selling the odd, useless invention on Amazon or buying up a chain of foreign liquor stores or installing a secret garden on the roof of my apartment where the helipad used to be. No, I do not know what Bayesian rationality is.”

I chuckled. “It’s based on Bayes’ theorem, which states that the probability of something being true is contingent on two things: how sensible it is based on prior evidence, and how well it fits the new evidence. So let’s say you have two suspects in front of you: a thief who is known to rob people every night when they’re asleep-”

“Oh,” Zac held up his hand. “Like when you’d steal my gourmet vegan hot chocolate powder every night while you were staying at my place? Over a few months, it just dwindled until one day it completely disappeared.”

“Yes, Zac. Exactly like that. Imagine a hot chocolate thief like myself — a known thief. You saw me commit the crime over and over and over again. I’d spoon it into my mug right in front of you while making eye contact, just to get a reaction.

And now imagine someone else in the house who has no track record of ever stealing anything, let alone your hot chocolate. Someone like-”

“Jamaal?” Zac suggested. “He would never touch chocolate. It would interfere with muscle formation.”

“Yes, Jamaal,” I agreed. Jamaal was a thirty-something-year-old American who rented a room in Zac’s Colombian penthouse. He spent half the time on the phone to his employees in the US, and the other half increasing the circumference of his biceps.

“Now,” I continued, “imagine that it had come to your attention that your hot chocolate powder had completely disappeared. You hold a hearing in the dining room with all five housemates present. Jamaal and I are both led in, heads hanging low in shame, hands fastened behind our backs with those fluffy pink handcuffs I found on your floor that time and-”

“Hey!” Zac interjected. “Those weren’t mine! They were-”

“Irrelevant, Zac. Silence! The hearing is about to begin. You stand at the head of the dining room table, bang your 3D-printed gavel against the wood and announce that the gourmet hot chocolate powder has completely disappeared, seemingly into some kind of black hole or alternate universe or-”

“Black hole,” Zac mused. “That’s a great word to describe your mouth. Chocolate cannot escape the gravitational pull of that infinite abyss. Hang on…” He reached over and grabbed his phone from the bedside table. “I just need to make a note of this for future reference. It’s always helpful to pre-prepare little witty insults.”

“Whatever,” I sighed. “The hot chocolate is completely gone, and you know for sure that one of us did it: it was either Jamaal or me. Given the prior evidence that I have been caught red-handed repeatedly committing the crime, and Jamaal has never been known to steal anything, who is more likely to have done it?”

“Obviously you. Duh. That’s why I now lock my chocolate in the safe.”

“Exactly!” I said. “Obviously me. Now, you can’t know for sure that it was me because there is always the possibility that Jamaal is secretly hoovering hot chocolate into his pie-hole when no one is around to catch him. But just given the limited prior evidence, it’s more likely that I did it.”

“And how does this relate to the universe?” Zac asked.

“We know for sure that one of these statements is true: either reality and consciousness are the same thing, or reality and consciousness are not the same thing. We have plenty of prior evidence that consciousness is a brilliant illusionist — it constructs a reality for us every night when we fall asleep and enter a dream. Sometimes it’s so convincing that I wake up from a horrible nightmare and think, ‘Oh thank God that’s over.’ You know — kind of like what your lady friends say as they wander out of your room looking dejected and unsatisfied-”

“What?! Excuse me! I’m an excellent-”

“Zac! Shush…” I held a finger to my lips. “I’m talking here. Have some respect. Now, on the other hand, we have zero evidence that reality is even capable of existing separate to consciousness. It could, but we just don’t have any evidence for it and we never will.

That assumption is kind of like Jamaal. He could be secretly shoveling hot chocolate down his gullet, but when the alternative suspect is myself — a known hot chocolate thief, someone who has a track record of committing the crime — the more likely explanation is that I did it, or that reality and consciousness are the same thing. Does that make sense?”