I would risk having to give my life for anything that would fill my personal requirements for being important or fundamentally right enough to justify the act. Mind you I wouldnt give my life for a 50/50 maybe. If I could end wars around the world for the next 50-100 years, yeah, I'd do it in a heartbeat, but if I found myself in a situation where say I and a friend was about to be killed and there was no chance of saving said friend but I had a chance to get away then I would do that without hesitating as well, mind you, those that I indeed consider firends I would take a bullet for any day. It all depends, if by saving a complete stranger I would have to ensure my own death then again, no I dont believe I or any one else that does not suffer from immensely bad self esteem and depression would do such a thing. Mind you, this can be subject to personal beliefs as, for an example one happends to be old and frail while able to save the life of a child, that would change the situation for many, or perhaps a pregnant woman. But these criterias again rest upon the individual belief in a persons inherant worth in keeping on living being greater than ones self and in most of those cases the instinct for self preservation would likely be to high to overcome.