Let's get a sense of proportion about disproportion.

This week David Cameron joined his shadow foreign secretary William Hague in denouncing elements of Israel's operations in Lebanon as 'disproportionate'. This view has not gone down well with some on the hawkish Right, but it has been met with approval among the Conservative Arabists and lefty humanists who think that everything Israel does is disproportionate.

Very few of the hawks, or lefties, or Arabists, however, seem to know what proportionality in war really means, or how Israel, in particular, understands it.

'Proportionality' is an element of Just War theory. This body of thought, which has evolved in Western philosophy from Augustine through Aquinas, is the framework through which almost all Western leaders, consciously or unconsciously, view warfare. It springs in part from one of the key principles of moral philosophy: that the end cannot justify the means. In Just War theory, proportionality has a role in both 'jus ad bellum' (the rules which determine whether you may wage war at all) and 'jus in bello' (the rules which determine what you may do during the war). In the first category, the theorists postulate that it cannot be just to wage war when the possible harm done by the war is disproportionate to the possible good which will result. In the second category, it is impermissible to attack a specific target of the opponent's when the possible collateral damage will be disproportionate to the military value of the target.

That does not mean that any attack which causes collateral damage is deemed to be unjust. The first test is whether you deliberately target non-combatants. If you do so, your action is …