Also quick but oh so necessary - Back40 Jones points to UMich complex polymath prof Cosma Shalizi's lengthy notebook-post on Ethics, Game Theory, and Biology:
One of the ideas I'm very fond of is that virtue isn't its own reward, it's a dominating strategy. More precisely, I am interested to see how far one can go towards showing that behaving ethically is actually a very good bet if one wants to come out ahead materially. Obviously there are times when nice guys lose, but it is an ancient observation that even a band of robbers must observe certain principles of morality among themselves, or perish. (So ancient I won't bother to try to run it down. See, however, Strauss's Persecution and the Art of Writing.) How far can we go with such reasoning?
The experiments of Robert Axelrod seem to indicate that a stance of "Be nice to everyone, but if someone hits you, hit back" is a very good bet. (When The Matrix came out, one reviewer, I think it was Stuart Klawans in The Nation, described the hero as "a Boddhisatva with compassion for all living things and the firepower to back it up": just so.) Sam Bowles and Herb Gintis have worked up from Axelrod's Tit for Tat to "strong reciprocity", explored in many technical papers and a great non-technical essay (below). This leads to a kind of social contract: we all agree to wallop the first guy to wallop anyone else. They would go further, and add a clause about agreeing to help each other out, until we catch someone cheating, at which point we wallop them, too.
Nice if we can get it to work; but why should we want to say, go out of our way to punish cheaters? Why should we want to cooperate? Clearly, we need some emotion which pushes us in that direction; to steal a useful phrase from Adam Smith, moral sentiments. Why should those evolve? Part of the answer, to my mind, comes from the work of Robert Frank, who showed, pretty convincingly, that sentiments like loyalty, honesty, love, and, yes, vengence have important material functions. They provide solutions to coordination and commitment problems, which make certain kinds of profitable undertaking possible in the first place. But they only do this if they are compelling (so you can't back out), and they are hard to fake. There is still a puzzle about how they could have evolved in the first place, but that's much more tractable...
If you're interested - and you should be, if for no other reason than the fact that this kind of shit makes for great party conversation ('I'm passionate, yet scientific'), if you're at the right party talking to the right kind of people - plz check out the link-filled bibliography at the bottom of the post, and the above-mentioned Bowles/Gintis 'non-technical essay' in particular, which uses these concepts to interrogate our ideas about welfare and other redistributionist, egalitarian policies - if you want to get political, and it is getting to be that (multiply heinous) season, potent intellectual firepower for Clintonite 'mend it don't end it' progressive centrist types in particular, esp when deployed against the Workers World wing of the Dems and/or the Pure Asshole wing of the Repubs -