Prisoner’s Dilemma
- is a game analyzed in game theory
- it is a thought experiment that challenges 2 rational agents to a dilemma:
- they could cooperate with their partner for mutual reward
- or they could betray their partner for individual reward
- The prisoner’s dilemma also illustrates that the decisions made under collective rationality may not necessarily be the same as those made under individual rationality
Matrix
|
Prisoner B stays silent |
Prisoner B betrays | |
|---|---|---|
|
Prisoner A stays silent |
Each serves 2 years |
Prisoner A: 10 years |
|
Prisoner A betrays |
Prisoner A: goes free |
Each serves 5 years |
Strategy
The best strategy is to choose “defect”
Because:
- If B cooperates, A should defect, because going free is better than serving 2 years
- If B defects, A should also defect because serving 5 years is better than serving 10
So, either way, A should defect since defecting is A’s best response regardless of B’s strategy. Parallel reasoning will show that B should defect.