Yesterday I got into a familiar discussion with a friend of mine about the nature of selfish deeds. Egoism is a valid moral theory. If everybody would act egoistic, than it would obviously be to everybody's advantage to strife for a society where that would work and that of course is pretty much the way our capitalistic world works.
The familiar discussion was not about egoism per se, but more whether there is such thing as an unselfish deed. It is easy to argue that there isn't because if we act rationally, we do what we want and if we do what we want, we're acting selfish in a way. Heroic self-sacrifice made the hero feel good, so really he did it for himself.
The argument is too simple to be useful in a moral discussion and should be sidestepped. If I tell you that you are begin selfish, I'm not pointing out an tautology. To accuse someone of being selfish, means something and therefore not all deeds are selfish.
To argue that all deeds are selfish depends on a logical falacy similar to the slipery slope. We take a term used in daily life, analyse it and then extend it meaning in a seeming logical way until the term is so overstretched that it means nothing and from that we draw a certain conclusion. The falacy is easily spotted. If somebody argues that something doesn't exist, we should ask ourselved, if it doesn't exist, why do we have a word for it? Does the word we have refer to the thing that doesn't exist or does the word means something and have we drifted off in our philosophical reasoning?