Historically, there have been two camps in this debate. One says that there is absolutely such a thing as true altruism, and it is possible to give to others at your own expense. The other says that all altruism is based on the selfish desires of making yourself look good or feeling more at peace about your other less-than-altruistic actions. Both sides have somewhat strong arguments and there is no reason why the argument wouldn't continue into perpetuity.
But I am going to spice up the argument a little bit and toss a third candidate into the fray: pure laziness. I don't know what else to do with them and seemingly all of my classes are changing the textbook next semester, so I have decided to donate my textbooks to apparently needy people in Africa. While I suppose that they might need the books more than I do, my real reason for doing so is that I am too lazy to send them across the country to California. I would argue that more altruism stems from laziness than one would otherwise presume. I call this theory the "Procrastination from Econ Theory." If you'd like, leave a comment and let me know if you agree with it or not. I am more serious about this than you'd probably assume.