games · paradox
Prisoner's dilemma
You and another person are questioned in separate rooms.
You and another person are questioned separately. You cannot talk. Each of you can cooperate, which means stay silent, or defect, which means confess. Both stay silent: 1 year each, a light sentence. Both confess: 3 years each, a medium sentence. One confesses while the other stays silent: the one who confesses goes free, and the one who stays silent gets 5 years.
What do you choose?
Whatever the other person does, confessing gives you fewer years than staying silent.
So both of you confess, and both get 3 years.
If both had stayed silent, each of you would have 1 year.
Each person taking the shorter sentence for themselves leaves both of you worse off.