system
Given the following post, respond as if you're commenting on Reddit:
human
In game theory is there a name for external events that that cause people to cooperate/defect without credible threats?

Sorry for the weird wording. I'm thinking a long the lines of many player iterated prisoner's dilemma or tragedy of the commons type problems. 

Eg. There's a bank run. People can either withdraw their money or not. Everybody is defecting, but would prefer that nobody defected. The government declares that they will make sure everybody gets their money from the bank. People think that other people will quit defecting because of this, so they quit defecting. It doesn't actually matter if the government does anything other than make the statement. 

Is there a name for events that cause people to quit/start defecting?
gpt
Perhaps you're thinking of a sunspot equilibrium? That's when they'd some information that's immaterial, in the sense that it doesn't affect payoffs, but it does affect people's actions just because people believe that it does.