I can honestly and 100% truthfully say that Phantom, Rinenud and Sangwa are my heroes, and I spend hours emotionally flogging myself over the fact that I will never be so skilled and verbose, yet witty and charmingly cunning at the same time.
As to the biological argument, its quite well studied the effects of certain neurotransmitters on both decision making, as well as consequence realization and remorse. One day, if I can be arsed, I'll look up the results of some of the studies conducted on known sociopaths. There is, if I remember correctly, a noticeable difference in the levels of serotonin and dopamine in those individuals who seem to show a significant lack of "morality."
Even beyond that, a lack of basic neurotransmitters in the brain, i.e. those which are present universally at synapses, would cause there to be no processing of information such as the two statements regarding mortality and Socrates, at many levels. Without these chemicals, one would not be able to integrate the electrical impulse at the primary visual center, nor shift it to the visual association area of the cortex, as well as the numerous other known functional areas, such as the prefrontal for analysis and decision making. So, one would not even be able to make it to the "thinking" stage about said statements to even begin to draw conclusions without said chemicals.
More to the point however, it is a sad fact that most evil villains are indeed vigilante-d in a most ridiculous fashion. There have been a few RPs I have been in where to play my character true to form, she would have intervened and stopped the murder of some other poor, unfortunate soul. But that would have been no fun as far as the RP was concerned. So instead, with about as much feeling and emotion as a 14 day old corpse, she began to try to pull the murderer away. [Read that as: help, help, oh won't someone help..is that a butterfly? I think it is... what a lovely butterfly... oops, that poor guy died while I was over here.] Which while being just a smidge OOC for my character, allowed the RP to continue in a way that was more beneficial to the scumbag.
Someone should start a Villain Protection Agency. Seriously, let's all exercise that frontal lobe and try a little common sense. If you break your toys, you won't have any left to play with.