All killing in war comes down to self-defense. This is a view that has become increasingly widespread among political philosophers over the past decade or so.
Essentially, the only way we can justify killing anyone ever is that it's done in self-defense, with some exceptions for saving others. This means that war is just self-defense on a grand scale. There's no fundamental moral difference between ordering an army to defend a nation and shooting someone who has broken into your home to rob you.
This belief about self-defense makes a lot of intuitive sense in the big picture, but it turns out to pose a serious challenge to the traditional view of just war theory. And not everyone is convinced that self-defense is the right way to justify war.
What about an American fighter pilot bombing al-Qaeda leaders meeting far off the front lines in Afghanistan? There are probably good reasons to think that kind of attack is justifiable, but do we really want to have to draw a line of individual self defense from the fighter pilot far above the battlefield all the way back down to those al-Qaeda leaders?
And what about civilians? If civilians are contributing to the war effort by bankrolling it—think about oil-company executives in Syria or officials at the Syrian central bank—shouldn't it be OK to kill them too? But that would contradict our deeply held belief that it is unacceptable to target civilians in war.
Seth Lazar is concerned about putting self-defense at the core of our beliefs about just war theory. He is a research fellow at the School of Philosophy at the Australian National University.
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