During the trench warfare
of World War I, peace broke out.
It was Christmas 1914. Despite strict orders not to chill
with the enemy, British and German soldiers left their trenches,
and gathered to bury their dead, exchange gifts, and sing. This wasn't unique. Even long before Christmas, soldiers already had an unspoken system of "live and let live" -- a small peace in a Great War.
Meanwhile, the West is now at peace, and yet, we distrust our governments, media, and each other more and more. So, we gotta ask: Why, even in the best of times, do friends become enemies? But also why, even in the worst of times, why do enemies become friends?
These are complex questions, but a simple idea from game
theory can help shed some light! So, to understand
our epidemic of distrust...

...let's play a game. →

THE GAME OF TRUST:
There's a machine. If one player puts a coin in the machine, the other player gets three coins. A player can either choose to COOPERATE (put in one coin), or CHEAT (keep their coin).

But there's a problem. Think about it: if the other player CHEATS, what should you do?

Fair enough – if the other player won't cooperate, why should you?

Alas, turning the other cheek just gets you slapped on that cheek.

Cooperating while the other person cheats means you lose a coin while they get three. (-1 vs +3) However, both of you cheating means you both neither gain nor lose anything. (0 vs 0) Therefore, you should CHEAT.

But if the other player COOPERATES, what should you do now?

Wow, that's mean. And also the correct answer!

Yeah, seems like the right thing to do... but is it the *correct* thing to do?

Because, if you both cooperate, you both lose one coin and gain three (+2 vs +2). But you can do even better – if you cheat while they cooperate, you can gain three coins at no cost, while they lose a coin. (+3 vs -1) Therefore, you should still CHEAT.

blah blah blah blah. But what if...

...we play more than once? →

COPYCAT: I start with Cooperate, and then, I just copy whatever move you did last time. Meow
ALWAYS CHEAT: i hate you
ALWAYS COOPERATE: I love you! <3
GRUDGER: "Listen y'all – I start Cooperatin', and I'll keep on Cooperatin'... but if you ever Cheat me once, pardner, I AIN'T EVER FORGIVIN' YOU."
DETECTIVE: "First: I analyze you. I start: Cooperate, Cheat, Cooperate, Cooperate. Then: if you retaliated with a Cheat, I switch to playing Copycat. But: if you never fight back, I switch to Always Cheat. My dear Watson: elementary."
now what if these characters were to play...

...against each other? →

It's tournament time! These five characters will now play against each other – 10 paired games, 10 rounds per game.
Place your bets: who do you think will get the highest *total* score?

next match

COPYCAT! (Note: this play-style is also known in game theory as "Tit For Tat")
Congrats, you placed your bet on the right horse.
Sorry, //////.
Now, here's the strange thing: Copycat can _never_ beat another player in the trust game (because it never tries to take advantage of others), it can only ever do _as well as_ the other player. And yet overall, Copycat wins! This, despite being simpler than Detective, nicer than Always Cheat, and more forgiving than Grudger. It almost seems to imply that the Golden Rule is not just a moral truth, but a *mathematical* truth:
*Do unto others as you would have them do unto you.* ~Copycat
And *that's* why "peace" broke out in the trenches of World War I. Each side was playing a deadly game of trust with each other, but because the nature of trench warfare means they have to face the same group of soldiers over and over again, that allowed a Copycat-like strategy – the unspoken law of "live and let live" – to evolve.

...but does Copycat *always* win? →

step

Start off with this distribution of players:

The payoffs in a one-on-one game are:

reset payoffs

Play [N] rounds per one-on-one game

Play [N] round per one-on-one game

After each tournament, eliminate the bottom [N] players & reproduce the top [N] players

After each tournament, eliminate the bottom [N] player & reproduce the top [N] player

In each round of a one-on-one game, there's a [N]% chance a player makes a mistake

blah blah blah blah blah blah blah blah
blah blah blah blah blah blah blah blah
blah blah blah blah blah blah blah blah
blah blah blah blah blah blah blah blah

<3

Copycat

copycat

Always Cheat

cheater

Always Cooperate

cooperater

Grudger

grudger

Detective

detective

Copykitten

copykitten

Simpleton

simpleton

Lol So Random

random

cooperate

cheat

play

stop

step

reset

population

payoffs

rules

1) play tournament

2) eliminate bottom 5

3) reproduce top 5

next

0. Introduction

1. One Game

2. Repeated Game

3. One Tournament

4. Repeated Tournament

5. Making Mistaeks

6. Sandbox Mode

7. Conclusion

Credits