If you have not done so, please read parts 1, 2 and 3 before proceeding.
Now that we have seen how ‘intention’ works we can move on to the third criteria for PDE:
3. The good effect cannot be achieved through the completion of the bad effect; in other words, the good effect must come about as a result of the action itself and not as a result of the bad effect.
Another way of phrasing this is to say the ends do not justify the means. Even if you have a good end, or goal, in mind and even if you do not intend the bad effect to occur your action would nonetheless be wrong to do if you achieve the good effect through first achieving the bad effect. Either the good and bad effect must occur simultaneously or the bad effect must come after the good effect, otherwise you would be doing something bad that good may come of it, which is always immoral.
The doctor, for instance, is causing pain to the child by putting a needle in him, but it is happening at the same time that he is preparing to test for diseases. So the doctor has both a good end and a good mean. This also applies if you divert the train onto another track or defend yourself even to the point of taking a life. These are all things in which your intended goal is not done through the completion of the bad effect first.
Let us go back to the train analogy to see how this criteria could be violated. Let’s say that rather than diverting the train onto the track with three people in order to avoid your mother on the original track you instead take three people and throw them in front of the train in order to force the train to stop, thus saving the life of your mother. While your intention to save your mother’s life is good in and of itself your throwing people in the path of the train is an ‘ends justify the means’ situation; it is through the killing of those three people that your mother is saved, thus making it a violation of the third criteria and thus immoral to do.
“Wait a minute,’ you might interject. “I do not agree with the necessity of this criteria in the first place! Why is it inherently wrong to do something, even something bad, so that good may come of it? Does the good end NEVER justify the bad means? Even if the bad means was something small and the good end was something great?”
That is precisely what I am saying.
It is ALWAYS immoral to do anything bad that good may come of it. Even if we had a situation where we could cure cancer but we first had to murder one innocent child to do it, it would still be utterly wrong to do that action. In such a situation it may seem crazy to many people not to do it, but it is actually crazy to even think about committing such an act. For the reason why it is wrong to achieve a bad means for the purpose of a good end is the exact same reason why it is wrong to achieve a bad end at all: because bad, or evil, by its definition is something that goes against what should be done.
That is the only reason one can give for not doing a bad thing in the first place. If something is wrong to do then you simply do not do it, for it goes against the moral code that is imbedded in us and ultimately works for our own good, whether we realize it or not. If that is why we should not do a bad thing, though, then the same logic must apply to a good end achieved through an evil or immoral means.
Evil should not be done precisely because evil is something that in its very nature goes against what we should, or ought, to do.