 If we got to the point where nobody could make their tweets any more searchable, would we have finally reached a hash equilibrium? War sucks, and is expensive. Most people, even most politicians agree on this, but we still make it a priority as a nation to pay for it. Why is it that the United States spends $820 billion every year, that's two and a half Googles on weapons and people who use them? Well, part of the answer has to do with game theory. It sounds like what happens when somebody takes a half hour to take a turn in risk, but game theory is actually a field of mathematics dedicated to analyzing complex situations and determining the best choices for players in those situations. For example, let's say that you're a prisoner, and the warden has offered you a deal. If you rat out a fellow prisoner for bad behavior, then you'll get set free and she'll get her sentence extended. But she secretly gets the same offer, and if you both end up ratting each other out, then you'll both end up with extended sentences. However, if you both manage to keep your trap shut, then you'll both get out a little bit earlier than you would normally. How are you supposed to decide what to do if you can't be sure what she's going to do? The answer is actually really complicated. This is a classic example of game theory called the prisoner's dilemma, and although it might just seem like kind of a dumb logic puzzle, the math developed to answer this question has been applied successfully to economics, science, psychology, ethics, and most notably in political science where it's played a huge role in warfare. Like let's say that you're a country and you have an opportunity to make a really powerful weapon. If you make the weapon and nobody else does, then you basically have free reign to demand whatever you want. But it's only a matter of time before somebody else figures out how to build it to defend themselves from you, and pretty soon everyone has invested the resources to make their own. I mean we could all just agree not to build it, which would be great because then we could spend all of those googles of dollars on stuff like Google, but we'd still have to worry about somebody eventually building one and upsetting the balance. Game theory has the same answer for both the prisoner's dilemma and the weapon problem. If you're strictly looking out for your best interests, then you should be the first one to sell out. It sounds like a crappy thing to do, but if the only thing that you care about is the length of your sentence or your safety, then mathematically the best choice is this square. And at the beginning of the Cold War that's exactly what happened. Given the threat of annihilation and the potential benefit of military superiority, the United States and Russia both expended massive amounts of resources to stockpile enough nuclear weapons to destroy each other several times over. But the power of those weapons led to a weird situation, even by game theory standards. You've probably heard of mutually assured destruction, which is a form of Nash equilibrium, a special state in game theory where nobody can improve their situation by changing their decision. If your enemy has the same power to utterly destroy you as you do to destroy them and a direct attack would just result in both of you being annihilated, that's not going to be an improvement to your situation. No sane person would ever do that, so you're both better off just sitting on top of your nuclear stockpiles and glaring at each other. But if you're thinking that way, and they're thinking that way, and you know that they're thinking that way, couldn't you attack and be pretty sure that they wouldn't retaliate? I mean, as soon as you've launched your nuclear arsenal they're already doomed. Are they really going to double world-wide casualties just out of spite? They'd have to be crazy. Well, yeah. So to maintain that Nash equilibrium your enemies have to think that you are that crazy. And if you've ever wondered why things got so hysterical during the Cold War, that's why. Like President Nixon consulting with political scientist and game theorist Henry Kissinger would actually behave as though he was prone to bouts of impulsive and irrational behavior just to convince other countries that he was crazy enough to use nuclear weapons. So mutually assured destruction is inherently insane on some level, and it's done a lot to foster paranoia between nuclear powers. But you can't argue with its track record. Hiroshima and Nagasaki are still the only two military targets of nuclear weapons in human history. My question is, will we ever be in a position where we can stop spending money on the upkeep of a nuclear arsenal? Or is the Nash equilibrium of everybody being armed to the teeth just the way that things have to be? Well, game theory only really works if all of the factors that can influence someone's decision, called payoffs, are accounted for and weighed accurately in its models. Like if everyone playing a game of Monopoly only cared about how much money they had at the end of the game, and played according to a perfect algorithm that maximized their income and minimized their risk, the game would be very long and very boring. But thankfully, people who play Monopoly care about more than that. They value entertainment and drama and laughing about getting stuck in jail repeatedly and finishing before dinner. So that algorithm doesn't always apply. In a similar vein, despite the fact that game theory clearly dictates that the prisoners and the prisoner's dilemma should rat each other out, studies on real prisoners show that they're actually more likely to keep their mouths shut. Why? Well, maybe they're thinking about retaliation from other prisoners, or they don't trust the warden, or maybe there is loyalty among thieves. If the game theory model for the nuclear arms race during the Cold War had some other payoffs besides military superiority or absolute destruction for the US and the USSR, maybe it would play out differently. Or maybe military force won't always be the bottom line. In a post-scarcity world or an artificial reality where everybody can have anything that they want, maybe there won't be anything to gain by threats of violence. Maybe, just like Monopoly, nations will someday discover that they don't really value pushing each other around anymore. Maybe they'll realize that they'd just like to be the top hat. Please leave a comment below and let me know what you think. Thank you very much for watching. Don't forget to blah, blah, subscribe, blah, share, and I'll see you next week.