Huvudkomponenter i Spelteori (PAPI):
- Spelare: Vem som fattar besluten (personer, företag, länder).
- Aktioner: Vilka handlingsalternativ spelarna har.
- Information: Vad spelarna vet om de andras strategier.
- Utbetalningar (Payoffs): Vad spelarna får ut av resultatet (vinst, förlust, strafftid)
The Nash Equilibrium in real life
The Nash equilibrium in real life. You are stuck in traffic. It’s a complete gridlock. You look to your left and there’s a lane that seems to be moving slightly faster. You look to your right, same thing. You desperately want to switch lanes. But here’s the problem. Every other driver is thinking the exact same thing. If you move, you slow down that lane. If they move, they slow down yours. Eventually, everyone settles into lane. And even though the traffic is terrible and everyone is miserable, no single person can improve their travel time by switching lanes unilaterally. You have entered a Nash equilibrium.
This concept is the bedrock of modern strategy.
And unfortunately, it explains why so many aspects of your life feel stuck.
A Nash equilibrium describes a state in a game where no player can benefit by changing their strategy while the other players keep theirs unchanged.
It is the mathematical definition of a stalemate.
Think about standing at a concert. At first, everyone is sitting comfortably. Then, one enthusiastic fan in the front row stands up to get a better view. Now the people behind him can’t see, so they stand up. This ripple effect moves all the way to the back of the stadium. Eventually, everyone is standing. The view is exactly the same as when everyone was sitting, but now your legs are tired and you can’t sit down because you’ll see nothing. You are trapped in a Nash equilibrium. The optimal group outcome, everyone sitting, is unstable because the individual incentive to stand is too high. This law governs everything from nuclear arms races to why you feel compelled to wear a suit to a job interview even though everyone would be more comfortable in pajamas. We are locked in suboptimal traps because we cannot trust others to coordinate with us.
The Ultimatum Game
The ultimatum game, fairness versus logic. Imagine I offer you $100, but there is a catch. I have to split this money with a stranger in another room. I can offer that stranger any amount I want from one penny to the full $100. If the stranger accepts my offer, we both get the money. If the stranger rejects my offer, neither of us gets anything. The stranger knows the total is $100.
Now, pure logic, the kind economists used to believe ruled the world dictates that the stranger should accept any offer greater than zero. Even one penny is better than nothing, right? A purely rational profit maximizing agent would take the penny. But that is not what happens. In real life experiments conducted all over the world, if I offer anything less than about 30%, say I try to keep $70 and give them 30, the vast majority of people will reject the offer. They will choose to walk away with nothing just to ensure that I also get nothing. This is the ultimatum game and it reveals a hidden mechanism in our brains that overrides basic math. The instinct for altruistic punishment. We are hardwired to punish unfairness even at a personal cost. This isn’t just pettiness. It’s an evolutionary safeguard. In a tribal setting, letting someone get away with hoarding resources was a death sentence for the group. So, we developed a fairness switch that effectively says, ”I will burn this entire deal to the ground rather than let you exploit me.” This is why you get irrationally angry when someone cuts in line, even if it only delays you by 5 seconds. It’s why revolutions happen. We aren’t profit maximizers. We are fairness enforcers. And knowing this changes how you negotiate everything from your salary to who does the dishes. You aren’t negotiating numbers. You are negotiating perceived respect. Why selfishness is mathematically predictable.
The prisoner´s Dilemma (Fairness vs Logic)
Let’s look at the most famous scenario in game theory, the prisoners dilemma. Two bank robbers are arrested and put in separate interrogation rooms. The police don’t have enough evidence to convict them of the major crime, only a minor one. They offer each prisoner a deal. If you betray your partner and testify against him, you go free and he gets 10 years.
If you both stay silent, you both get just one year for the minor charge.
But if you both betray each other, you both get 5 years. The math is cruel here. No matter what your partner does, your best individual move is always to betray him. If he stays silent, you betray him and go free. If he betrays you, you must betray him to avoid the 10-year sentence. Defection is the dominant strategy. This explains the depressing architecture of modern cynicism. Why do politicians run attack ads? Because if one side takes the high road, stays silent, and the other attacks, defects, the attacker wins. Why do athletes take performance-enhancing drugs? If everyone stays clean, the best athlete wins. But if your opponent is doping and you aren’t, you lose. The logic of the prisoners dilemma forces us into a race to the bottom where rational individuals produce a distinctively irrational group outcome. We lock our doors not because we hate our neighbors, but because we cannot mathematically ensure they won’t rob us. We stockpile resources not because we are greedy, but because the cost of being the sucker who didn’t stockpile is too high. Selfishness isn’t always a moral failing. Often, it’s just people who are good at math but bad at trust.