The Principle of Double Effect

The Conditions There are certain conditions which must be observed before one may perform the action in question. Should any of these conditions be violated, one may not perform the action.

The Conditions 1. The action itself (which has two effects) must be a good action, or at least morally indifferent. In other words, it cannot be an evil act. Otherwise, we'd be doing evil to achieve good.

The Conditions 2. One must not positively will the evil effect. That is, one must not intend the evil effect. One may only permit or allow the evil effect. Permitting and intending are two very different ways of relating to human goods.

The Conditions 3. The good effect must proceed directly from the action and not from the evil effect. For this would involve doing evil to achieve good.

Here, the good effect proceeds from the evil effect. If this were the scenario, one would have to will the evil effect in order to achieve the good effect. This violates the second condition. For one must not will evil for the sake of a good.

The Conditions 4. The good effect must be sufficiently desirable to compensate for the allowing of the evil effect.

Intending vs. Accepting No one intends to wear out their shoes. One wills that they never wear out, that they last forever. But one accepts the inevitable. One accepts the fact that when I choose to wear my shoes, they are going to wear out.