Study Guide: The Prisoner's Dilemma
Introduction
The Prisoner's Dilemma is a classic game theory problem that is frequently used to study human behavior in various fields, including economics, political science, and psychology. This study guide will explore the basics of the Prisoner's Dilemma and provide an overview of key concepts.
Basics of the Prisoner's Dilemma
The Prisoner's Dilemma is a game where two players must make a decision without knowing what the other player will do. Each player has two choices: cooperate or defect. The outcomes of the game depend on the choices of both players. The following matrix shows the payoffs for each player:
|
Player 2 Cooperates |
Player 2 Defects |
Player 1 |
|
|
Cooperate |
(3, 3) |
(0, 5) |
Defect |
(5, 0) |
(1, 1) |
As seen in the matrix, if both players cooperate, they both receive a reward of 3. If one player cooperates and the other defects, the defector receives a higher reward while the cooperator receives a lower reward. If both players defect, they both receive a small reward of 1.
Rationality and Dominant Strategy
In game theory, players are assumed to be rational actors who will make decisions that maximize their own payoff. A dominant strategy is a strategy that will always yield the highest possible payout for a player, regardless of the other player's strategy. In the Prisoner's Dilemma, there is a dominant strategy for each player to defect, since no matter what the other player does, the player who defects will receive a higher payoff.
Nash Equilibrium
A Nash Equilibrium is a situation in a game where neither player has an incentive to change their strategy, given the other player's strategy. In the Prisoner's Dilemma, the Nash Equilibrium is for both players to defect, since neither player can gain a higher payoff by switching to cooperate.
Iterated Prisoner's Dilemma
The Iterated Prisoner's Dilemma is a variant of the game where each player plays multiple rounds of the game with the same opponent. In this version, players can use their opponent's previous moves to inform their current decision.
Conclusion
The Prisoner's Dilemma is a fundamental concept in game theory that has important implications for understanding human behavior. It demonstrates the challenges of cooperation in situations where the best outcome depends on mutual cooperation, but there are incentives for each individual to defect.