The Doctrine of Double Effect

Such collateral civilian casualties can be excused while still maintaining it is wrong to take deliberate aim at civilian targets [1]. In just war theory, the doctrine of double effect introduced by Thomas Aquinas offers the justification for just this kind of damage[2]. It is a way of reconciling the absolute prohibition against attacking noncombatants with the legitimate conduct of military activity. The doctrine itself argues that acts have two (“double”) effects, one directly intended and the other foreseen but not intended.. Thus double effect allows for the intentional targeting of legitimate military objectives, and writes off the civilian casualties incurred as foreseeable, yet unintentional or “accidental” effects. It applies in ambiguous situation when noncombatants (or friendlies in cases of fratricide) are mistaken for combatants – what matters is that the intention was a legitimate target in the mind of the actor. The following case from the Iraq War illustrates the consequences of US troops having right intentions yet creating disastrous consequences by failing to accurately distinguishing noncombatants from enemy:

[Civilians] drove about in vehicles easily mistaken for the ‘technicals’ [civilian vehicles co-opted into military role] used by fighters…. The result was a spectacle of dead fathers or slaughtered children in bullet-ridden cars skewed across the roadway; incensed American soldiers, stricken with guilt at what they had done, took refuge in feigned indifference.[1]

Rejecting the doctrine of double effect regards such “collateral” harm to noncombatant as either deliberate or intentional. Moral responsibility for civilian deaths must be accepted apart from some other justifying or excusing circumstances[2].

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[1] John Keegan. The Iraq War, (London: Hutchinson, 2004), 200.

[2] David R. Mapel. “Realism, War and Peace” in Terry Nardin (ed.) The Ethics of War and Peace: Religious and Secular Perspectives, (Princeton: Princeton University Press, 1996), 67.