Principle of Double Effect - Intentional Harm Versus Side Effects

Intentional Harm Versus Side Effects

Although different writers state and employ double effect differently, they share the position that consequentially similar acts having different intentional structures make for ethically different acts. So, for example, advocates of double effect typically consider the intentional terror bombing of non-combatants having as its goal victory in a legitimate war morally out of bounds, while holding as ethically in bounds an act of strategic bombing that similarly harms non-combatants with foresight but without intent as a side effect of destroying a legitimate military target. Because advocates of double effect propose that consequentially similar acts can be morally different, double effect is most often criticized by consequentialists who consider the consequences of actions entirely determinative of the action's morality.

In their use of the distinction between intent and foresight without intent, advocates of double effect make three arguments. First, that intent differs from foresight, even in cases in which one foresees an effect as inevitable. Second, that one can apply the distinction to specific sets of cases found in military ethics (terror bombing/strategic bombing), medical ethics (craniotomy/hysterectomy), and social ethics (euthanasia). Third, that the distinction has moral relevance, importance, or significance.

The doctrine consists of four conditions that must be satisfied before an act is morally permissible:

1. The nature-of-the-act condition. The action must be either morally good or indifferent.
2. The means-end condition. The bad effect must not be the means by which one achieves the good effect.
3. The right-intention condition. The intention must be the achieving of only the good effect, with the bad effect being only an unintended side effect.
4. The proportionality condition. The good effect must be at least equivalent in importance to the bad effect.

The second of these four conditions is an application of the more general principle that good ends do not justify evil means (cf. Romans 3:8).