The Principle of Double Effect Part 3: The Intention

If you have not done so, please read part 1 and part 2 before proceeding.

Having seen that an action must be morally good or morally neutral as part of the Principle of Double Effect (PDE), we now turn towards the second criteria:

The person intends the good effect to happen but does not intend the bad effect to happen; he/she merely allows or has knowledge that the bad effect will happen.

The idea of ‘intention’ is arguably the most well-known and most important aspect in understanding PDE, for it focuses directly on the person’s psychological interaction with the good and bad effect of an action.

Basically, this step says that if you intentionally choose to do an action because of the good effect and not because of the bad effect, then it may be permissible for you to do the act. Whereas, if you intentionally choose to do an act because of the bad effect, then it is not moral for you to do that action.

As long as the doctor intends to draw blood for the purpose of testing for disease and not for the purpose of causing pain then, assuming all other criteria are met, it is acceptable for the doctor to withdraw the blood. But if the doctor is drawing blood because he wants to cause the child pain then it will be immoral for him to do the act, even if he simultaneously desires to do it for testing. If the bad effect is ever intended then it is immoral to do the act. It’s the same thing with the train tracks analogy. As long as you do not intend to kill the people on the other track and are only pressing the button to save the life of your mother, then it can be morally acceptable to push the button.

The third example, defending yourself from another person even to the point of killing that person, was the original analogy used by St. Thomas Aquinas when he discussed The Principle of Double Effect (though he did not call it by that name). If you need to kill someone in order to defend your life or the life of another, then it may be acceptable for you to do so provided that you do not intend the death of the attacker; you must merely intend to defend your life. If a police officer sees an attacker start raising his gun, he is perfectly within his moral right to shoot him first, as long as he simply desires to stop the gunman from shooting at him and does not intend to actually kill him.

“But wait!” you might say. “What if the police officer knows that the person will die if he, say, shoots him in the head? What if he has 100% certainty that that will happen. Doesn’t that mean that he intends to kill the attacker? And thus wouldn’t it be wrong to shoot him according to PDE?”

The answer to both questions is not necessarily. This is because there is an inherent difference between intending and knowing. You can know that something is going to happen without deliberately choosing or wanting it to happen. The doctor certainly knows that sticking a needle into a child’s arm will cause some pain and discomfort, but it does not at all follow that he wants to cause the child harm. It is something that the doctor simply ‘allows’ or accepts. Similarly, you are certain that once you push the button and the train is diverted that the other three strangers will be killed by the train. But it does not necessarily mean that you want or choose for those people to die; you simply choose to divert the train to save your mother, even though you know that three people will be killed in the process.

Thus, despite knowing that the attacker will die as a result of his actions, the police officer, nonetheless, does not intend for the attacker to die. This is the fundamental difference in Catholicism between killing and murder. Killing, in and of itself, can be acceptable so long as one does not intend the death of the other; if they do then that would be murder.

This barely even scratches the surface of the idea of intention. Numerous scholarly articles have been dedicated to exploring what intention is and how it applies to everyday life. But hopefully there is enough here to show the importance of one’s intentions when making a decision on a moral act.