Doctrine of double effect

The doctrine of double effect is a thesis in ethics, usually attributed to Aquinas. Although different writers state the doctrine in different ways, it always claims that there is a moral difference between courses of action such as the following:

1. An agent deliberately causes harm in order to promote some good.
2. An agent promotes some good in such a way that harm is caused as a foreseen side-effect.

The doctrine of double effect claims that the first action is morally worse than the second, all other things being equal. The name comes from the "double effect" in the second sort of action.

Applications

The doctrine has practical applications, for example in just war theory, where the deliberate targeting of civilians to demoralise the enemy may be ruled out, but the bombing of munitions plants may be allowed, even if both actions cause the same number of deaths and end the war in the same length of time.

The doctrine is also relevant to certain medical cases. The administration of a high dosage of painkillers is sometimes allowed for the relief of pain in cases of terminal illness, even when this will cause death as a side effect. Some hold that this is morally different from deliberate euthanasia for the relief of pain.

Controversy

Despite some apparent plausibility, the doctrine of double effect is controversial. Utilitarians, in particular, reject the notion that 2 acts can differ in their permissibility, if both have the same consequences.

See also: Trolley problem