The comments on my post yesterday about Glenn Greenwald were interesting, and seemed to indicate a bit of confusion between different matters. So here's a quick lexicon of relevant terms:
Manslaughter: the unintended killing of a person. In all systems of law I've ever heard of, manslaughter is less serious than murder, even though the consequence for the victim is the same: death.
Murder. The intentional taking of an innocent life. It's the intention that makes the difference, not the result. In Right to Exist: A Moral Defense of Israel's Wars I pointed out that the Sixth of the Ten Commandments is not "thou shall not kill", as often mistranslated, but rather "thou shall not murder". Judaism recognizes that killing sometimes happens, such as in self defense or in war.
Self defense. Protecting oneself may sometimes include killing. When evaluating the act, it's not the result - the death of a person - which is important, it's the intention. Of the attacker. The court or the police may decide that killing the aggressor was justified by the intention of the (dead) aggressor.
War. This is the most common way for people to kill large numbers of other people. The mere fact of being at war tells very little about morality, since some wars avert worse things, such as genocide, others promote genocide, and many wars happen for complicated reasons which do not immediately lend themselves to moral deliberation. I have written about this at greater length here.
Terrorism. Initially, this wasn't a moral category at all. It was a tactic of random murder, intended to terrorize a society into changing its behavior in a significant manner, contrary to its will, perpetrated by an otherwise small or weak group. The phenomenon first appeared in the 19th century. Then a double twist occurred.
The first was in the 1980s. At the time the most famous terrorist group was the PLO (alongside the IRA). Lots of people were reluctant to use such a pejorative word to describe Arabs killing Jews: The Arabs had oil, they were supported by the Soviets and thus also by Western Useful Idiots, the Jews were, well, Jews. So the term was dropped, replaced by the term 'militants'. So cynical was this ploy that for years the international news of the BBC called the PLO militants, while the local news of the same BBC called the IRA terrorists. (I'm not making this up). The English language lost the word to describe the people who had once been militants, but this seemed a worthy price to pay for political correctness.
Then, after 9/11, suddenly there was an urgent need for a clearly pejorative word to describe the perpetrators of random murder committed by a small group with the intention of terrorizing an entire society. At the time I remember watching the agonizing, but it didn't take long for the American media to go back to the obvious word, 'terrorist'. Once the terrorists began exploding bombs on European trains, the word was accepted worldwide. (Interestingly, this was happening parallel to a steep decrease in Palestinian terrorism, forced by the IDF and the security barrier, so the dilemma of using the word for everyone except the Jews was blunted).
Yet there was a problem: lots of people didn't like the ensuing wars, nor the regrettable fact that Western troops were now killing Muslim civilians. So they started applying the terrorist word to them, too. There was no need, of course, since armies killing civilians as a result of the messiness of war were never previously called terrorists. Armies aren't small groups; the Western ones were not randomly killing innocents so as to terrorize them. It would have been better to use a different term, one that would do what language is supposed to do, namely describe reality with useful preciseness. But preciseness was the last thing the wielders of the term were seeking; their goal was to bludgeon the political discourse in their ideological direction.
And so we've come full circle and kept on going. Not only is the word terrorism back in vogue, it's now applied with a gusto to anyone who kills non-combatants, unless they're Islamists killing Muslims, in which case they're called insurgents. (And the Palestinians are still militants).
Glenn Greenwald's argument demonstrates how radical this is. Back in 1976, when Michael Walzer published his seminal Just And Unjust Wars: A Moral Argument With Historical Illustrations, a book still widely cited, he included a discussion of intentionally killing non-combatants in a non-belligerent country. The Allies had reason to believe the Germans were developing nuclear weapons, and at one point had to decide to sink a Norwegian ship which might have been transporting heavy water but was certainly carrying regular Norwegian civilians; the Norwegians, remember, were notionally on the Allies' side. Yet the danger of a Nazi nuclear bomb was so great it was decided to sacrifice random innocent Norwegians to prevent it. The fact that by the time Walzer wrote his book it was long since clear that there had in fact been no Nazi nuclear program to be thwarted was irrelevant, since the decision makers couldn't have known that and had reasonable reason to believe the opposite. After he works through the matter as philosophers do, Walzer justifies the decision.
Greenwald, facing a lesser case where someone killed an Iranian nuclear scientist without scratching any innocents at all, calls it terrorism.