Dr. Helen has some thoughts. I'm with Mark Twain and Heinlein on this issue, myself. Every action we take is, ultimately, for ourselves, if for no other reason that it makes us feel good.

I think that is a useless way of looking at it, myself. Essentially, you are saying that we only do the things that we tell ourselves to do. While true, it doesn't add much meaning to life.

The real question, I believe, is this: what is the pain/reward allocation between myself and others that I am willing to acept. For example, which of the following actions would you take:

Action A: you are rewarded greatly, others are rewarded less
Action B: you are rewarded greatly, others are rewarded greatly
Action C: you are rewarded less, others are rewarded greatly
Action D: you are rewarded greatly, others are harmed a little
Action E: you are rewarded greatly, others are harmed a lot
Action F: you are harmed a little, others are harmed a lot

Most people would do A and B. There are some people that would not do C - they do not feel good unless they are "best". Many people would not do D, but many do - cheating on your taxes or profitting from destroying a common good are examples. Few people do E, and very few do F - but they do exist.

It all comes down to what makes you happy. Most people are happy when they make others happy - we are just wired that way. Some people are happy when they hurt others - most of us agree that they are defective.

To me, anyone that chooses to do actions A, B, or C are altruistic. Those that do D are self-centered, and those that do E and F are dangers to society and need to be eliminated or repaired.

Sorry, that last paragraph should have said "anyone that chooses to do ONLY actions A, B, or C are altruistic"

To put it more simply, you can judge rationality by seeing if your actions are in your best interests. You judge altruism by determining if your actions are in other's best interest.

I'm with Mark Twain...

The link would indicate that you are Mark Twain.

What of the religious tradition dictating anonymous charitable giving? That argues for or against the existence of altruism?

Few people do E...

And I've worked with all of them.

Every action we take is, ultimately, for ourselves

Nah. Sounds like you've forgotten how we came to be here (unless you believe in Divine Creation, and not evolution). Each one of us is here only because he's a representative of a successful and highly social species, one which -- because of its lack of claws, speed, fangs -- is nothing but meat for the nearest carnivore except when it acts in coordinated groups.

Hence every action we take is, ultimately, for the good of the tribe. It often benefits us as individuals, too, but there are many clear and important cases (e.g. sex and childbearing) in which actions individuals feel compelled to take are quite good for the tribe but generally deleterious for the individual. *

It suits Mother Nature to wire into our DNA urges and feelings of great satisfaction when we act in ways that improve the tribe's survival probability, even when it degrades our own. Apparently we're happier and more productive when we can talk ourselves into believing we're free to choose, even when we're not.

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* And of course, the tribe also always needs a few outliers who defy conventionality in this and other ways, to keep a source of wacky and improbable ideas and behaviours on tap for the rare situation in which they're useful. Hence even folks who deviate from the social norm widely are acting quite socially, ironically.

David, you miss a few choices. For example, you are harmed a lot while others are harmed a little. This technically is altruistic behavior in the economic sense though often is not in the usual sense. For example, the buddhist monks (in Vietnam) that protested the war in Vietnam by setting themselves on fire versus damaging an ex-lover's car publically and getting jailed for it because there are a zillion witnesses who saw you do it.

The great Austrian-school economist Israel Kirzner, in a course of his I took at NYU, said there was a completely uninteresting way to discuss self-interest, which is to define it to include altruistic acts that give us a sense of moral satisfaction. For reasons I find hard to articulate, I think he was right.

Also, the philosopher John Searle has done some work on 'desire-independent' reasons-- that humans (unlike chimps say) can be willing to pay for a beer because they committed to paying for it (not because they wanted to pay; what they wanted was the beer).

The bad Mark Twain link stays?

I fixed it this morning.