Double
Effect
What is the Double Effect Principle?
The double effect principle is an exercise in philosophy, titled Doctrine of Double Effect and first accredited to Thomas Aquinas, and according to the Stanford Encyclopedia of Philosophy, “emphasizes the distinction between causing a morally grave harm as a side effect of pursuing a good end and causing a morally grave harm as a means of pursuing a good end” (McIntyre, 2018). Put differently, some decision can be justifiably moral, according to Aquinas, if the harmful side-effect caused by the decision was not the intention. However, decisions become immoral when the harm is caused for “the common good” as harm is no longer an unavoidable side effect but the intention.
How does it relate to nuclear weapons?
As you may already have connected, the principle of double effect is very relevant when discussing the use of nuclear weapons as they are almost certainly to cause a “fallout” so to speak. That is to say, when using nuclear weapons, the side effect of the decision is almost certainly the loss of innocent lives. In a recent paper titled Double Effect, Wicker (2019) uses a non-war example to clarify what relationship the double effect has to nuclear weapons, he states,
“Now, let us suppose that killing bees has been forbidden by law, on environmental grounds, whereas killing flies is allowed. And let us suppose that driving down the motorway inevitably leads to the deaths on my windscreen of some bees as well as of some flies. And further let us suppose that, despite the ban on killing bees, my friend Fred has still asked me to collect some flies for his research. I decide to do this while visiting my Aunt Edna by driving down the motorway. Now, we have agreed that killing any insects on my windscreen will be only a side-effect of the action of my visiting my Aunt Edna. But killing the flies will still be a direct effect of the action of my doing what Fred has asked me to do. And both of these action-descriptions will be true of what I am (basically) doing. But now, while killing the flies will be excusable (because there is no ban against doing it even as a direct effect of my action), killing the bees is a criminal offence for which I may be guilty. This means that, under the description: ‘I am obeying Fred’s request by driving down the motorway’ one effect of what I am doing will be excusable as a licit direct effect, while the other will be condemned as a criminal offence.” (p. 451)
In the example above, Fred has asked us to kill some flies (current war enemy) and so we decide that the best way to do this is to visit our aunt and collect them while driving down the highway (dropping nuclear weapons). Whilst doing this, however, we notice that we are also killing bees (innocent people) which is illegal and can lead to criminal action. The purpose of this example is to illustrate that while dropping nuclear weapons, like driving your car to collect flies, may be the most efficient way to end wars with enemy nations we must remember that there are direct and indirect side effects that both need careful consideration.