Damn, sundaybastard! I have had this argument using the same logic you used, over and over, and I lose every time. What do you have that I don’t? You’re good!
I will throw this into the mix: evolutionary biologists tend to analyze all behavior in terms of survival value. Apparently we aren’t built just to consider our own survival, but the survival of our group, or species. This is why some people are willing to sacrifice themselves for others, such as soldiers who might throw themselves on a grenade to save their buddies, and others who die to save someone else.
I think that all this might change if we are more careful about our definition of altruism. If we define it as actions that bring more immediate benefit to other individuals than to the person taking the action, we might not have a debate. Yes, helping someone else may have a kind of karmic effect which eventually returns to benefit you; and yes, helping another person is a kind of social glue that creates the expectation of reciprocation even though we do not, ostensibly, do it for that purpose; but in the near term, we are doing something for someone else, not ourselves.
We could test this. I know a number of people here who have said that they do altruistic actions with no expectation of return. We could tell them to go be altruistic, and make sure they get no return, not in status or approval or anything. We could see how long they kept up the altruistic work. My bet is that it wouldn’t be long before they would be bemoaning the damn ingrates they were trying to help, and soon after that, they’d give up on their altruistic behavior.