Originally Posted by Vlerchan
: I can't think of any logical basis, i.e., a basis that doesn't appeal to emotion, to deliberately disadvantage oneself. 
I've had second thoughts about this.
I believe that individuals engage in altruistic behaviour mainly in the name of a 'greater good', etc. and not so much in the name of ego: whilst the need to feel good about oneself might exist, I feel that its subordinate to, and thus not as influential as, ones want to serve the 'greater good': since the latter illogical want factors in more than the former logical want, I feel that people are not acting as much (i.e., fully) in their own self-interest as you might be making out - and thus are acting illogically. 
I'd argue that pure altruism doesn't exist, but altruism itself can be a major factor in an individuals decision making process.
There's no such (objective) thing as the 'greater good' and thus acting in its name is illogical. 
Again, I ask for a logical basis in which one would deliberately disadvantage oneself, gaining neither a return or a full-return on their actions. It seems to me that any such action would be necessarily influenced by emotion. 
I was making the point that your opinion is irrelevent to whether something is logical or not.
: There can be plenty. You can deliberatly disadvantage yourself because you know it will help others, or to achieve something else , etc.
: Even if they aren't acting for themselves, that doesn't make it illogical. Evolutionairy speaking we could definetly have completely altruistic traits that disadvantage ourselves but help our species or children survive.
: Sorry, I didn't mean "The
greater good", I just meant a greater good, whichever that might be in the situation.
: Does that make it illogical? I know emotional actions and arguments are not logical, but acting in a certain way to allow yourself to feel an emotion can be based on logical decision making.