It can be argued that the basic principle of civilization is "Thou shalt not kill." This is not just an arbitrary religious dictum. The essence of civilization--cities as opposed to villages--is lots of people living together and using their energy cooperatively to produce much more than what is necessary for survival. People who don't know each other, people who aren't related. People who have no instinctive reason to trust each other.
Civilization only works if these people don't have to be constantly looking over their shoulders to protect themselves by attacks from their fellow citizens.
Civilization will BREAK DOWN if we can't trust each other. We'll be back in the Stone Age, leading a life obsessed with survival, where every tribe is wary of every other tribe and they are careful not to cross into each other's territory. With a technology and an economy that won't support the existence of six billion people on one planet.
You do not get to kill ANYBODY, EVER, FOR ANY REASON.
Of course there are obvious exceptions that hardly need justification. People who are hopelessly ill, suffering in pain and/or indignity, whose sustenance requires so many resources that it's a drain on their community, and who ask for mercy killing. People who get a rush out of taking risks and want to go into a bare-knuckle fighting ring against each other. Or perhaps even gladiators, I don't have a problem with that even though I would never watch it. As long as it's consenting adults and they're not using assisted suicide as a way to avoid responsibility to their children.
Self-defense? Well it seems obvious to me that if someone is trying to kill you or rape you, he has removed himself from the community of civilized people. Voluntarily removed himself from the jurisdiction of the rules. As a civilized person with a highly ingrained abhorrence for killing, you would of course make every attempt to neutralize the threat without deadly force, but if you have to kill him it doesn't violate the rule against killing because he volunteered to be exempt from it.
Defense of others? Sure. We all have a duty to maintain the structure of civilization, so we all have a duty to ensure that everyone feels safe and doesn't have to expend a lot of energy protecting themselves against each other. So if you see somebody trying to kill somebody else you not only have the right to stop him, you have a duty, to keep civilization from breaking down.
War? Screw all the sophistic arguments about what's fair and not fair in war. War is a total breakdown of civilization. Two nations at war have dropped out of the community and both have declared that the rules no longer apply to them. It's a mess because not everyone in either of those nations agrees with the decision, and it's our duty to save them from their stupid brethren. That probably means that we have the right and duty to kill all of the people in those nations who do agree with the decision. Right now, every nation on earth should be sending its armed forces, into Israel, Lebanon, Somalia, Chechnya, etc., and every other place where people are killing each other en masse. Those troops should be doing two things.
1. Kill all the killers. They have voluntarily removed themselves from civilization, so the rules don't apply. We can kill them all with a clean conscience. And we must do so to cleanse civilization.
2. Remove all the noncombatants. Airlift them, take them in boats, drive them in Humvees, walk them out surrounded by cordons of soldiers and covered by squadrons of helicopters. Yes, even the noncombatants we hate. The Lebanese Shiite families who believe in the cause of Hezbollah but haven't actually performed an act of violence themselves. The Israeli families who root for war but aren't fighting in it. (That might put Israel in a tough spot because isn't everybody there technically in the army and sworn to uphold the orders of the national leaders?) We might have to put some of those people in POW camps because we're not sure if they're ready to rejoin civilization. The ones who keep yelling "death to the Jews" or "death to the Muslims" or "death to America" or "death to the Ethiopians" might have to stay in camp for a good long time and we might have to take their children away to be raised in more civilized surroundings. But we don't get to KILL them because that would be uncivilized! We cannot kill people because of what they say or what they believe, only for what they do. We can restrain them, imprison them, but not kill them.
When we finally cleanse their countries of killers, probably by using WMDs which are okay against people who have voluntarily identified themselves as uncivilized and there's no risk to noncombatants because they're all away at camp, then we can return the civilians. We'll probably have to cordon off huge territories to use as rehabilitation camps and put the less trustworthy civilians through a recivilization process.
This sounds messy but it's better than the way we do it now. It sounds cruel but it's more humane than the way we do it now because the killing is concentrated on the people who believe killing is okay.
The problem is that we can't get the countries who aren't involved in the combat to agree that both sides are wrong. Everybody thinks that their ally is the underdog. I'm sorry, but the first time their ally kills a noncombatant civilian by a deliberate act of violence, whether targeted or just "collateral damage," they've removed themselves from civilization and they're not the underdog any more. They're just all dogs.
Dogs don't get to make the rules. Everybody gets to discipline a bad dog, even if it's not their own dog. It's called "civilization."
