Killing and The Psychological Cost.

[Aulus Perrinius]

It must be somewhat cultural. Some groups, ancient and modern, have little problem deliberately killing other people.

I know I would have problems with it, but in certain circumstances, might feel I had no choice to protect my family or myself, or perhaps in the combat line of one sort or another (not much chance of that now, at age 60). What would be my thinking after ending someone's life? I don't know, and frankly, don't want to know. Maybe I can get to the end of mine without taking anyone else's. I'd like that.

Agreed. From what I've read, Social and Cultural distances are huge factors.

After all, telling yourself you shot a human being is hard. Telling yourself you popped a 'Dink', 'Slant', 'Gook', or 'Kraut' is much easier.