Two scientists, a hundred rounds of a simple game, and a story about two prisoners — the grid that shows why clever people so often refuse to cooperate.
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Ten items. Say your answer out loud before you reveal it.
Read the sentence, guess the meaning of the word in bold, then reveal.
The three words are: rational · think tank · arms race. Read each meaning, say the word, then reveal.
One missing word fits every phrase in the group. Say it, then reveal.
Read each part. After it, answer the quick check from memory, then discuss one question.
In 1950, the Cold War was just beginning. The Soviet Union had tested its first atomic bomb the year before, and the United States wanted to understand how nuclear powers might behave. One place that studied this question was the RAND Corporation, a new think tank in Santa Monica, California, paid largely by the US Air Force.
Many RAND researchers used game theory — the mathematics of decisions where your result depends on what someone else does. In January 1950, two RAND mathematicians, Merrill Flood and Melvin Dresher, designed a simple game for two players. Each player could choose to cooperate or not. If both cooperated, both did quite well. But whatever the other player did, each player could always do a little better for himself by not cooperating. The rational choice, according to theory, was never to cooperate.
Flood and Dresher asked two colleagues to play the game one hundred times in a row. The theory said they should refuse to cooperate every time. They didn't. Again and again, the two men tried to cooperate — and got annoyed when the other one didn't.
1. Why was the US government interested in RAND's research?
2. What was the “rational” choice in Flood and Dresher's game, according to theory?
3. What did the two players actually do?
1. Because of the Cold War — it wanted to understand how nuclear powers might behave.
2. Never to cooperate, because not cooperating always gave a slightly better individual result.
3. They often tried to cooperate, far more than the theory predicted.
A few months later, a Princeton mathematician, Albert Tucker, was asked to explain the game to a group of psychologists at Stanford. To make the idea easy to follow for people who were not mathematicians, he turned it into a story.
Two suspects are arrested and put in separate rooms. They cannot talk to each other. The police make each of them the same offer. If you confess and your partner stays silent, you go free and he gets ten years. If you both stay silent, you each get one year. If you both confess, you each get five years.
Think it through. If your partner stays silent, confessing is better for you: zero years instead of one. If your partner confesses, confessing is still better: five years instead of ten. So you confess — and so does your partner. You both get five years, although you could both have had one. That is the dilemma: two people each make the sensible choice, and both lose. Many people at the time saw the same trap in the arms race, where each superpower kept building bombs because it could not trust the other to stop.
1. Why did Tucker tell a story instead of using numbers?
2. If both prisoners stay silent, what happens?
3. Why is the result a “dilemma”?
1. His audience were psychologists, not mathematicians, and a story made the idea easier to follow.
2. They each get one year.
3. Each prisoner makes the sensible choice (confess), but together they end up worse off than if both had stayed silent.
In real life, we rarely meet someone just once. Colleagues, neighbours and countries deal with each other again and again. So what is the best strategy when the game is repeated?
Around 1980, Robert Axelrod, a political scientist at the University of Michigan, invited experts from many fields to send him computer programs that would play the game against each other, round after round. Some programs were long and clever. The winner was one of the shortest: a program called Tit for Tat, sent in by the mathematician and psychologist Anatol Rapoport. Its rules were simple. Cooperate in the first round. After that, copy whatever the other player did last time. Axelrod ran a second, bigger tournament. Tit for Tat won again.
Axelrod drew four lessons from it: be nice (never be the first to betray), retaliate (don't let betrayal go unpunished), forgive (return to cooperating as soon as the other player does), and be clear (make your strategy easy to understand). Today the game is used to study price wars, climate agreements, doping in sport and even friendships between animals.
1. Why is a repeated game different from a single game?
2. What are the two rules of Tit for Tat?
3. Name two of Axelrod's four lessons.
1. Because you will meet the same player again, so what you do now affects how they treat you later.
2. Cooperate in the first round; after that, copy the other player's last move.
3. Any two: be nice, retaliate, forgive, be clear.
The tool is a payoff grid. Prisoner B's choices run along the bottom, Prisoner A's up the side, and each box shows what both players get. Here, the numbers are years in prison — so lower is better.
Use the grid and the rules of Tit for Tat (cooperate first, then copy the other player's last move). For each question, choose cooperate (stay silent) or betray (confess).
1. Betray — going free beats 1 year, and 5 years beats 10.
2. Cooperate — 1 + 1 = 2 years, the best total.
3. Cooperate — Tit for Tat always starts nicely.
4. Betray — it copies the other player's last move.
5. Cooperate — it forgives immediately.
6. Betray — it retaliates — once.
People aren't only calculators. Loyalty, guilt and friendship change the “payoffs” — as Flood and Dresher's players showed on day one.
Real life is noisy. If a cooperative move is misunderstood as betrayal, Tit for Tat can get stuck in an endless cycle of revenge.
Not every conflict fits. Many situations have more than two players, more than two choices, or players who can talk.
The whole game is built on conditions: if you do this, I'll do that. At B2 you need more than if. These words let you set conditions precisely.
Write unless, as long as, otherwise or even if. One of the words is used twice.
1. I'll lend you the money you pay me back by Friday.
2. The shop will close next year more customers start coming.
3. Book your tickets now. , they'll be sold out.
4. She'd never cheat, she knew nobody would find out.
5. You won't pass the exam you start studying.
1. as long as
2. unless
3. Otherwise
4. even if
5. unless
Keep the meaning, using the word in brackets.
1. If you don't hurry, we'll miss the bus. (unless) →
2. You can stay, but only if you're quiet. (provided) →
3. Save your work now, because if you don't, you might lose it. (otherwise) →
4. It doesn't matter if it's expensive — I'm buying it. (even if) →
1. Unless you hurry, we'll miss the bus.
2. You can stay provided (that) you're quiet.
3. Save your work now. Otherwise, you might lose it.
4. I'm buying it even if it's expensive.
Now write the rules of Tit for Tat in your own words, using as long as and unless.
Use the game to think about trust in your own life. Choose a task, start the timer, and talk.
Describe a situation — at work, at home, in your city — where everyone would gain by cooperating, but people don't.
Are you a Tit for Tat person? How do you react when someone lets you down, and how quickly do you forgive?
Choose one shared problem, such as traffic, litter or noise. What rule or promise would make cooperation the smart choice?