Four Conditions of the Doctrine of Double Effect

The following outline and discussion of the four conditions needed to satisfy the doctrine comes primarily from Walzer[1]. The first of these considers the act in and of itself, or is at least indifferent, that is, it is a legitimate act of war. This is an important safeguard as it can be used to subsequently test against the assertions made in the second and third factors. These next two are complementary as they concern ends and means – the second factor asks if the direct effect is morally acceptable (for example, the killing of enemy soldiers), while the third requires intention of the actor is good, aiming only at the acceptable effect; the evil is not one of his ends, nor is it a means to his ends. Fourthly, the good effect must be sufficiently good to compensate for allowing the evil effect; it must be justifiable under the proportionality rule.

The third clause carries the weight of the argument. In it, coterminous good and evil effects, are defendable “only insofar as they are the product of a single intention, directed at the first and not the second”[2]. Within the double effect analysis, “right” intention is that which resolves to attack only legitimate targets, following the principle of discrimination. This is the direct effect. All harm to civilians, even though foreseeable, must have been unintended. These are the indirect effects of the action.

A number of issues can be raised concerning the justification of foreseeable breaches of immunity, as well as the balance to strike between military legitimate military activity objectives and civilian casualties. The unintended but foreseeable deaths of military action can be great in number, subject only to the proportionality rule. This is essentially that hostile action against enemy should be controlled and confined to that which is necessary for the achievement of mission objectives. However this is not a strong constraint, as what is proportional or excessive relies on the judgement of the warrior on the spot. Considerations of proportionality easily slide into arguments favouring “military necessity” where “moral judgements wait upon military considerations”[3]. In addition, it is arguable that it is irrelevant whether the civilians are dead as a consequence of the direct or the indirect effect of an action. They are still dead. How can moral blame be denied if military action is initiated in the full knowledge that innocents will be killed?

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[1] Walzer, Just and Unjust Wars, 153.

[2] Walzer, Just and Unjust Wars, 153.

[3] Walzer, Just and Unjust Wars, 129.