I've been reading a book called "The Survival Game" by David Barash. It's a discussion on game theory and I've found it to be quite interesting, particularly the bit on the concept of "live and let live" during WWI. Basically it is the idea that the soldiers on both sides were miserable enough with the cold and trenches (for an excellent documentary on the subject, you can check out the fourth season of Black Adder). Add other people shooting at each you and the whole event became something you would just as soon pass up. So the soldiers began to use the strategy of tit-for-tat. In other words, if you let me live, I'll let you live. I won't shoot at you, but if you shoot three times at me, I'm going to return as many bullets.
This concept became well known to both sides, much to the chagrin of the officers, who were supposed to be running a war, and were quite put out that their soldiers weren't cooperating. At times one side or the other would stand up out of the trenches and apologize for artillery attacks that they had no control over. During several Christmases, both sides were so comfortable with each other that several impromptu games of soccer were played.
Anyway, the other interesting part that has got me thinking is the concept of community rationality. The idea is basically that we all are rational, self-interested creatures, and act accordingly. But sometimes we act not in what is most rational for ourselves, but rather what is most rational for the community we belong to. I don't know whether I quite buy the fact that these rationalities are separate; it might possibly be that the latter is simply a different manifestation of the former, but still, I find the concept interesting.
Maybe this community rationality can help explain why people will act in ways that aren't directly tied to their own self-interest. They are a part of a community, and feel that by acting in such a way, the community will benefit, and maybe eventually it will even come back to help them. I recently heard about "Random Acts of Genealogical Kindness", in which people will volunteer to go out and take pictures of cemeteries, or look up information for other people, free of charge. Individually you have a hard time explaining this action, but when you look at the entire community, it starts to make more sense. I think GeoCaching is the same way. Without some kind of community rationality, the whole thing falls apart.