They have both done wrong already so they will rat each other out.Game theory defines rationality in a sense of selfishness, but there are other ways to define it.prior to last week I almost forgot that each human is designed as a game-theoretically optimized biological machine. In simpler terms: in the end, everyone is a selfish cunt
For example, let's take a look at the prisoner's dilemma:
Person A and Person B are being interrogated. If A rats out B, but B doesn't rat out A, A serves no time, and B serves 10 years. If A rats out B and B rats out A they both serve 5 years. If B rats out A, and A doesn't rat out B, A serves 10 years and B serves no time. If neither rats out the other they both serve 1 year.
Now, the usual way this is analysed, is that assuming this is a closed system, A serves less time in either case if they rat out B, and B serves less time in either case if they rat out A, so they would both rat each other out, and thus be much worse off than if they hadn't ratted each other out.
But what if the people involved looked at it like this: If A doesn't rat out B, then either the same or a lower amount of time will be served overall, and if B doesn't rat out A then either the same or a lower amount of time will be served overall. So, by looking at this from a selfless perspective, neither would rat out the other, and the total amount of time served is kept to a minimum.
I see no reason that the latter means of rationalisation is invalid or inferior to the former. I don't think it's really a proven thing that people in reality even stick to the former. There are probably aspects of both means of analysis, alongside all kinds of other motivating factors, at play in how people actually function.