Casper: There is a problem that I can't bring up without starting a fight.

Gregor: No, what?

Casper: It just seems so obvious to me. It has infiltrated every single Veritasium meeting in the last two months.

Gregor: It's trivial. (laughs) I didn't think you would fall for this side.

Casper: So, here's the setup. You walk into a room, and there's a supercomputer and two boxes on the table. One box is open, and it's got $1,000 in it. There's no trick. You know it's $1,000. The other box is a mystery box, you can't see inside. You also know that this supercomputer is very good at predicting people. It has correctly predicted the choices of thousands of people in the exact problem you're about to face. Now, you don't know what that problem is yet, but you do know that it has been correct almost every time. Now, the supercomputer says you can either take both boxes, that is the mystery box and the $1,000, or you can just take the mystery box. So, what's in that mystery box? Well, the supercomputer tells you that before you walked into the room, it made a prediction about your choice. If the supercomputer predicted you would just take the mystery box and you'd leave the $1,000 on the table, well, then it put $1 million into the mystery box. But if the supercomputer predicted that you would take both boxes, then it put nothing in the mystery box. The supercomputer made its prediction before you knew about the problem and it has already set up the boxes. It's not trying to trick you, it's not trying to deprive you of any money. Its only goal is to make the correct prediction. So, what do you do? Do you take both boxes or do you just take the mystery box?

Gregor: This is seeming less paradoxical than I thought because I should just go in and take the mystery box only.

Casper: No! What? There are two camps, one-boxers who would take only the mystery box, and two-boxers who take both. But as American philosopher Robert Nozick wrote, "To almost everyone, it is perfectly clear and obvious what should be done. The difficulty is that these people seem to divide almost evenly on the problem, with large numbers thinking that the opposite half is just being silly." This is known as Newcomb's paradox, named for its inventor, William Newcomb. The Guardian newspaper polled over 31,000 people about this problem in 2016. 53.5% were one-boxers and 46.5% were two-boxers.

Gregor: Look, I'm a reasonable guy and I like money, so I'm gonna do whatever gets me the most money. So, let's go weigh the outcomes of both of these decisions. First, I'm gonna say that the probability that the computer predicted my decision correctly is gonna be C... If the computer is better at predicting than what is basically random, then the expected utility of one-boxing is gonna be higher. Now, I know that the computer is much better at predicting than that because it accurately predicted thousands of people before me, which means I'm sticking with my one box. Here's my $1 million.

Casper: I'm very surprised. Because to me, the answer is also obvious, and to me, the answer is you take both boxes. You know that the supercomputer has already set up the boxes, so whatever I decide to do now, it doesn't change whether there's zero or $1 million in that mystery box... This is known as strategic dominance where I always pick the dominant strategy, which in this case is to two-box. So, give me those boxes.

Gregor: Here's the hidden assumption for us one-boxers. My expected utility calculations are based on probabilities that are using prior evidence of how accuracy the supercomputer is... This is based on something called evidential decision theory.

Casper: I make my decision based off something else, something a little more rational because I believe that whatever I do now can't influence and change the past... This is known as causal decision theory, where you only take into account things that you can actually cause.

Henry: You're not doing me a favor 'cause your decision making does not affect... Like, your little thought does not change God's mind, bro. Henry, if you convinced yourself that you're a one-boxer, you've convinced the machine. I don't believe that.

Casper: Because it actually reveals a surprising amount about three important questions. Does free will exist? What does it mean to be rational? And is there an ideal way to act in life? ...if such a perfect predictor would exist, does that mean that free will doesn't exist?

Henry: That's right, and maybe this reveals where I'm coming from... free will is an illusion, but our world operates in a way that is indistinguishable from free will being real, and therefore, you have to act as though it's real.

Casper: Which brings us to our second question, what does it mean to be rational?... This is known as the "Why Ain'cha Rich?" argument. In their 1978 paper, philosophers Gibbard and Harper argue that the rational choice is to pick both boxes. Although they do admit that two-boxers will fare worse. They instead say that the game is rigged.

Gregor: And I think this is analogous to the situation in the prisoner's dilemma... What's a rational society? A rational society is full of cooperators. What's a rational person? Maybe a rational person is a defector.

Casper: Now, say you are the US president during the Cold War. You have publicly committed to retaliate if the US is ever attacked... This strategy eventually became known as mutually assured destruction, or MAD. In the 1963 film, "Dr. Strangelove", the Russians built the perfect doomsday device... to prevent the Russians themselves from having second thoughts.

Gregor: Sometimes it's put in the form of, if you knew that you were a robot with programming, that you could set and you could rewire yourself... what sort of rules would you wire yourself to obey? And what you would do is you would make yourself into the kind of creature that sort of always acts in line with the commitments that would've been good to form had you even known about the problem.

Casper: Yeah, that would convince me to be a one-boxer. The core of Newcomb's paradox is deciding if a strong correlation that you know isn't causal should matter in your decision.