altruism and memory

I've been reading a fair bit lately about agent-based modeling. Basically, these are models of interactions between agents, each of whom decides for themselves how they will behave.

One interesting question that comes up is "why should I be nice to people, when that niceness has an associated cost?" For example, imagine that I share my lunch with someone. In that case, I end up with less lunch. So, it would seem that the most successful agents would not engage in such sharing activities.

But, by and large, people are kind to each other, which begs the question "why do people sacrifice in order to help others?"

In a very cold economic sense, the answer is that it is beneficial to sacrifice some resources, in order to help others, because those people will remember your kindness and repay you in future with kindness of their own (or you get a reputation as a good person, and other people are kind to you in future). And that payoff makes it worthwhile to be nice to other people.

Lately, I have spent a fair bit of time interacting with an elderly faculty member at UC Berkeley. These conversations typically start with me reminding this individual of who I am (which is not surprising, given his age, and the fact that I am by no means an "important" person in the Berkeley physics scene).

This got me to thinking about how altruism might play out in a world where people do not remember your good deeds, and thus there is no chance of you being repayed for your kindness.

In such a world, the economic value of kindness is significantly mitigated. If people make purely economic decisions, then, they would likely not engage in altruistic behavior.

I wonder how far such thinking would go in helping us to understand the workings of communities in which individuals are highly anonymous (if you are completely anonymous, you effectively interact with a memoryless populace, since no one knows who you are and thus cannot link your actions to some identity). These might include on-line communities, as well as large cities.

What's my point? Well, it might be a good idea to introduce yourself to your neighbors, and maybe to smile when you do so.