My logic tells me that altruism is an illusion. Even if you do something that appears to give you no benefit, you will still get some sort of satisfaction out of benefiting another person (i.e. you're fulfilling a previously made obligation to help, you feel more virtuous by doing a "selfless" act, you're happier because you aren't around someone who is upset about the thing you helped with, you feel you've increased your good karma, etc. [your particular benefit depends on both the situation and your personality]). That's not to say that acts we so often label as selfless are selfish; they're just more complex than many people's polar views of them. So my mind cannot see a situation that is truly altruistic, but my heart likes to think that there is nothing wrong with trying to be selfless, even if it is not humanly possible to succeed in that respect 100%.
What do you guys think? Do you believe true altruism exists?