The 'Just War' doctrine has made a reappearance, in the form of an endorsement from the Archbishop of Canterbury Justin Welby. The occasion was the debate in the British House of Commons to expand the air conflict against ISIL into Syria, in what is already a horrendously crowded airspace.
Speaking before members of the House of Lords on 2 December, Welby said: 'The just war criteria have to my mind been met, but while they are necessary, they are not by themselves sufficient in action of this kind.'
If Prime Minister David Cameron was hoping for a carte blanche blessing, he would have been disappointed. Britain might 'end up doing the right thing in such a wrong way it becomes the wrong thing', said Welby.
Resorting to aerial bombing, he added, 'plays into the expectation of ISIL and other jihadist groups in the region, springing from their apocalyptic theology: the totality of our actions must subvert that false narrative because by itself it will not work'.
As ever, lurking behind just war doctrine are fundamental contradictions, not least of all that it seems artificially neat.
A few of its elements are worth noting. Resorting to it should be of last resort when non-violent options are exhausted. It must be conducted by a legitimate authority. It must be directed to correct a suffered wrong, and done with right intentions. Prospects for success must be reasonable and inflicted violence must be proportionate. Distinctions between combatants and non-combatants should be maintained.
Theologians have been wrestling with these criteria for centuries, notably that pertaining to legitimate authority. Christian armies killing Christian armies make the issue of justice a rather odd affair, but there was always a scribe to provide an enthusiast's backing.
The whole basis of where the just war concept as a notion crept into common usage is also an unclear one, though one attribution — to St Augustine of Hippo — is not as convincing as it might be. He did, however, suggest rationales for war by combining the classical concept of war with religious morality:
'We do not seek peace in order to be at war, but we go to war that we may have peace. Be peaceful, therefore, in warring, so that you may vanquish those whom you war against, and bring them to the prosperity of peace.' War was sinful, but in being waged by sinners, it might be a legitimate corrective, a justification that