The Argument Expressed Diagrammatically
In our example of two co-workers on the bus, each person wants to get off the bus and get a drink only if the other person gets off also. A person’s motivations can be represented by assigning to each outcome a number that corresponds to its payoff or utility. For example, the worst thing for me would be if I got off and you stayed on, because I would feel bad about having a drink without you being there; this would give me a payoff of 0. The best thing for me would be if we both got off; we would enjoy a drink together and this would give me a payoff of 6. If I stay on the bus, I get the “status quo” utility of 4, regardless of whether you get off or not.
Assuming that you and I are similar, we can write down your utilities: the worst thing for you is if you get off and I stay on, and so forth.