Originally Posted by BWillie007
When I say "best interest" it is in the terms of the own individuals interpretation. Maybe a better word is "utility". Any voluntary action you take, you take that because you decided it would give your life/legacy/ etc the greatest utility. So, in the case of someone jumping in front of a car to save their loved one. They may value their loved ones life more than their own and it was the best option at the time, thus, giving them most satisfaction or utility out of any other option. If premeditated, say someone risked their life to diffuse a bomb they may seek fame even if it is posthumous of their good deeds.
My point is I believe all individuals are selfish in their own way.
That's utilitarianism, which states that all things are weighed out and the one that yields the best consequence is the act you perform. However, that runs into problems as well.