DOUBLE EFFECT PRINCIPLE

Developed during the 13th century by Thomas Aquinas, the Double Effect Principle, otherwise and more popularly referred to as the Doctrine of the Double Effect (DDE), is significantly applied in Catholic moral theology, ethics, war theory, law, and medicine. The DDE is a rule that’s used to comprehend when it would be morally acceptable to cause a bad result even if it isn’t your intended goal.

To put the definition simply, DDE argues that intentions of an action matter when we measure morality, not just the outcomes of an action. In the case that a harm does end up happening, it must be unintended, even if it is predictable. Some popular examples are killing in self-defense and bombing military targets which leads to unintended killing of civilians.

There are 4 main clauses that an action that led to a bad result must fulfill in order to be considered moral despite the result. The first is that the action must be morally good or neutral. For example, with the example of killing in self-defense, the action is morally good as you are intending to save your life. The second is that the bad effect must not be intended, only tolerated. Applying the previous example, one trying to defend themselves from a killer has the intention to survive, not the intention to kill someone. The third condition is that the bad effect must not be the means to the good effect. For example, you don’t HAVE to kill someone in order to keep yourself alive. And, more importantly, the force used was made with the intention of stopping harm; death is just a side effect, not a method. Finally, the fourth clause is that the good effect must outweigh the bad. When it comes to the self-defense example again, we’re saving an innocent life over the unjust attacker, which shows that the good has outweighed the bad. Thus, the self-defense example has been proven just in the Aquinas DDE example.

Some real life debates that are based on Aquinas’s DDE principles are bombing a military base that also kills civilians nearby (civilian deaths are foreseen, not aimed at); giving high doses of painkillers that ease suffering but may shorten life (shortening life is not intended); removing a fallopian tube to save the mother, but a fetus dies (fetus death is a side effect, not intended consequence); and the trolley problem, where the lever is only allowed to be pulled if you don’t use someone’s death as a tool to save others.

While DDE is used in legal and military systems to justify tough choices, many argue that DDE is very vague. Some argue that DDE is used as a way to rationalize harm by arguing that it wasn’t someone’s intention. Others argue that in the end, someone still dies and the moral impact of that is disregarded by DDE. DDE’s usage in military systems is also extremely controversial, as many argue that it’s just being used to justify violence and death. Finally, perhaps the most common argument of all, is that it is extremely difficult to decipher what one’s true intention really is.