I’m reasonable if, when you and I disagree, I’m willing to constrain or modify my pursuit of my own interests to the same degree that you’re willing to constrain or modify your pursuit of your interests. When we come together to suggest our rules, then, we aren’t just “looking out for number one.” Rather, we both want to design a world where we accommodate each other’s needs, so that when we don’t see eye to eye on something, finding a way to coexist in some kind of harmony becomes our top priority.