The prisoner’s dilemma is so famous it can fool you into thinking every strategic situation is one. It isn’t. Many of the most important games you’ll face have a completely different shape — and reaching for “defect, it’s dominant” when you’re actually in a game of trust or nerve will lose you the game. This final teaching lesson rounds out your repertoire with two more canonical games and one make-or-break mindset distinction. Get these and you’ll not only know the models — you’ll know which model you’re in, which is the whole point.
The stag hunt: a game of trust
Picture two hunters. Together they can take down a stag — a feast, far more than either could get alone — but only if both commit to the hunt; if one wanders off, the lone stag-hunter goes home with nothing. Alternatively, either can safely catch a hare on their own — a modest, guaranteed meal that doesn’t depend on the other at all. Stag is the big cooperative prize; hare is the safe solo fallback.
Payoff matrix
The stag hunt: the big prize needs trust
Hunting stag together pays best (4, 4) — but only if both commit. Hunting hare is safe and pays 3 no matter what the other does. Find the two equilibria with the rings.
| Hunter 2 | ||
|---|---|---|
| Hunt stag | Hunt hare | |
| Hunter 1Hunt stag | NE44 | 03 |
| Hunt hare | 30 | NE33 |
A ringed payoff is that player’s best response to the rival’s choice. A cell where both are ringed is a Nash equilibrium.
What the matrix says
Hunter 1 — dominant strategy: none
Hunter 2 — dominant strategy: none
Nash equilibrium (pure): (Hunt stag, Hunt stag) · (Hunt hare, Hunt hare)
Unlike the prisoner’s dilemma, there’s no dominant strategy here and no temptation to betray — if you’re sure your partner hunts stag, you absolutely want to hunt stag too (4 beats 3). The whole problem is uncertainty about the other player. Both-stag and both-hare are each Nash equilibria. Both-stag is payoff-dominant (better for both); both-hare is risk-dominant (the safe choice that protects you if your partner flakes). Which one a pair lands on comes down to trust: hunt stag only if you believe the other will too.
The stag hunt is the model for nearly every situation where cooperation is best for all but requires everyone to stick their neck out together: launching a startup with co-founders, a team adopting a demanding new process, citizens turning out for a revolution, two firms investing in a shared standard. The barrier isn’t greed — it’s the fear that you’ll commit and others won’t. That’s why trust, communication, and credible commitment (which are useless in a true prisoner’s dilemma) are exactly what unlock the stag hunt.
Dilemma or stag hunt? Diagnose before you prescribe
The two look similar but need opposite medicine. In a prisoner’s dilemma, defection is dominant — a mere promise to cooperate is worthless, because each still gains by breaking it; you need to change the payoffs. In a stag hunt, cooperation is already a best response if you trust the other; here a credible promise, a shared signal, or just talking it through can be enough to tip everyone to the good equilibrium. Misdiagnose, and you’ll waste enforcement on a trust problem or trust on an enforcement problem.
A team would all be better off adopting a demanding new workflow, but it only pays off if everyone commits; if some don't, the early adopters just suffer the extra work for nothing. No one is *tempted* to free-ride — they're simply afraid others won't commit. Which game is this, and what's the fix?
Chicken: a game of nerve
Now a nastier shape. Two drivers speed straight at each other; the first to swerve is the loser (“chicken”), but if neither swerves they crash and both are ruined. Each wants to hold straight and have the other swerve. The catastrophe — both holding straight — is the worst outcome for everyone, yet the temptation to be the one who stands firm is exactly what drives them toward it.
Payoff matrix
Chicken: the worst outcome is mutual toughness
Holding straight while the other swerves is the big win (5). Both swerving is a fine draw (3). But both holding straight is the crash (0) — the disaster each hopes to avoid by betting the other blinks.
| Driver 2 | ||
|---|---|---|
| Swerve | Hold straight | |
| Driver 1Swerve | 33 | NE25 |
| Hold straight | NE52 | 00 |
A ringed payoff is that player’s best response to the rival’s choice. A cell where both are ringed is a Nash equilibrium.
What the matrix says
Driver 1 — dominant strategy: none
Driver 2 — dominant strategy: none
Nash equilibrium (pure): (Swerve, Hold straight) · (Hold straight, Swerve)
Chicken is the structure of brinkmanship — pushing a confrontation toward the edge to make the other side back down. Its two pure equilibria are the mismatched cells: one swerves, one holds. The strategic twist is chilling: you can win chicken by visibly destroying your own ability to swerve — rip out your steering wheel and throw it out the window where your opponent can see. Now you can’t back down, so their only sane move is to swerve. Limiting your own options can be a winning move when it makes your commitment credible. Real-world chicken runs from labour strikes and debt-ceiling standoffs to nuclear deterrence and two startups burning cash in a market that only fits one. The danger is obvious: if both sides adopt the throw-out-the-wheel logic, you get the crash neither wanted.
It feels backwards that reducing your own freedom could help you. But in chicken, your problem is credibility: saying “I won’t swerve” is cheap talk, since when the crash looms you obviously will swerve to save yourself, and your opponent knows it. By making the commitment physically irreversible — tearing out the wheel, signing a contract with huge penalties for backing down, staking your public reputation — you turn the threat from a bluff into a fact. Now backing down isn’t an option you’d be tempted to take; it’s gone. Thomas Schelling won a Nobel Prize partly for this insight: in strategic conflict, a credible commitment is power, and the ability to bind your own hands can beat the freedom to keep them loose. The catch remains — if both sides do it, nothing can stop the collision.
The big mindset: zero-sum vs. positive-sum
Step back from individual games to the most consequential distinction of all — one that quietly governs whether you approach a situation as a war or a partnership.
A zero-sum game is one where the payoffs always add up to the same total, so one player’s gain is exactly another’s loss. There’s a fixed pie and the only question is who gets which slice: poker, matching pennies, dividing a fixed inheritance, two candidates splitting a fixed pool of votes. In zero-sum games, every gain for you is a loss for them, so cooperation is impossible by construction — it’s pure competition.
A positive-sum game is one where the total payoff can grow: through cooperation, trade, or clever arrangement, the players can create value that makes the whole pie bigger, so both can come out ahead. Most of economic life is positive-sum — voluntary trade happens precisely because both sides expect to gain (recall comparative advantage: two parties trading can both end up richer). A good negotiation, a business partnership, a marriage, a treaty that opens commerce — all positive-sum. (There are also negative-sum games, like war or a lawsuit, where the fighting shrinks the pie and players can both end up worse than when they started.)
The single most expensive strategic error
The costliest mistake in this entire course is treating a positive-sum game as if it were zero-sum — the fixed-pie fallacy. Believing “for me to win, they must lose,” you fight over slices instead of growing the pie: you refuse mutually profitable trades, turn partners into enemies, and leave enormous value rotting on the table. Most negotiations that could have made both sides better off fail because at least one party assumed the pie was fixed. Before you fight over the slices, always ask: can we make the pie bigger first?
Two companies could either fight a brutal price war for the same customers, or partner — one's great at manufacturing, the other at distribution — and together open a far larger market. A manager insists 'business is war; their gain is our loss.' What error is this, and what does it cost?
Sort each situation by whether it is fundamentally zero-sum or positive-sum.
Place each item in the right group.
- Dividing a fixed inheritance between two heirs
- Co-founders building a company worth more than either could alone
- Two countries opening trade that lets each specialise
- Two finalists competing for a single trophy
- Two poker players splitting a fixed pot
- A worker and employer negotiating a job that benefits both
Match each game or concept to its defining feature.
Pick a term, then click its definition.
Pin down the mindset.
Pick the right option for each blank, then check.
In a game the total is fixed, so one player's gain is another's loss; in a game cooperation can grow the pie so both can win. Treating the second as if it were the first is the fallacy, and it forfeits value both sides could have shared.
Recap
Big picture
Beyond the dilemma: a fuller map
- Other Games & Mindsets
- Stag hunt (trust)
- Cooperation best but risky; fix with trust & commitment, not enforcement
- Chicken (nerve)
- Mutual toughness = catastrophe; credible commitment (throw the wheel) wins
- Zero-sum
- Fixed pie — my gain is your loss; pure competition
- Positive-sum
- Pie can grow via cooperation/trade — both can win
- The big error
- Fixed-pie fallacy: fighting zero-sum over a pie you could have grown
- Stag hunt (trust)
When to use it
Before you strategise, diagnose the game. Is betrayal tempting and dominant (prisoner’s dilemma → change the payoffs)? Is cooperation best but scary (stag hunt → build trust)? Is it a test of nerve where backing down loses but crashing is worse (chicken → commit credibly, and beware the symmetric catastrophe)? And above all: is the pie fixed or could it grow? Answer that last question first, because mistaking a positive-sum situation for a zero-sum one is the error that quietly costs the most. You now hold the core toolkit. The final exam pulls it all together — players, matrices, dominance, equilibrium, the dilemma, repetition, and these last games of trust, nerve, and mindset. Reason each question through; several look easy until you notice which game you’re really in.