Technically, this isn’t part of the syllabus and all you need to know about it is some very basic stuff–just like Virtue Ethics. The typical question in which DDE shows up will test you on whether you can at least see that someone is trying to invoke it–whether successful or not, whether the doctrine itself is even true–stuff that’s already in Norcross . But if you want a more fine grain break down, here is is. (Do keep in mind that most of the below is optional as far as the syllabus is concerned.)

Let’s say that a certain type of outcome X is morally bad, so much so that the act of intentionally bringing X about is morally impermissible. DDE says that if the following conditions hold, then, it is permissible for A to do something that brings about X.

  • (a) The action that A does must itself be permissible (when considered by itself).
  • (b) A must not act so as to intentionally bring about X; that is, X is the unintended but unavoidable side-effect of what he was trying to achieve, let’s say, Y; if he could have brought about Y without bringing about X, A should do so.
  • (c) The outcome Y must be directly brought about by A’s action rather than via X (in other words, X must not to be the instrument or means for bringing about Y).
  • (d) The good of Y must outweigh the bad of X.

How does the above apply to the cases we have considered so far?

At the top of p. 234, Norcross paints his opponent as conceding DDE doesn’t apply to Fred and his puppies, but it does to the consumers of factory-farmed meat. But he (Norcross) disagrees–he believes that DDE applies to neither case. Even though he doesn’t think that DDE is a true doctrine, his argument is that–leaving that aside–the doctrine doesn’t even apply to the consumers of factory-farmed meat, because their actions fail to satisfy condition (d):

The Doctrine of Double Effect requires not merely that a bad effect be foreseen and not intended, but also that there be an outweighing good effect. In the case of the suffering of factory-raised animals, whatever good could plausibly be claimed to come out of the system clearly doesn’t outweigh the bad.

But he continues.

Furthermore, it would be easy to modify the story of Fred to render the puppies’ suffering ‘merely’ foreseen. For example, suppose that the cocoamone is produced by a chemical reaction that can only occur when large quantities of drain-cleaner are forced down the throat of a conscious, unanaesthetized puppy. The consequent appalling suffering, while not itself a means to the production of cocoamone, is nonetheless an unavoidable side-effect of the means. In this variation of the story, Fred’s behavior is no less abominable than in the original.

This is where Norcross goes on the offensive against the DDE itself by presenting a version of the Fred’s Puppies scenario that can technically satisfy conditions (a)-(d), and inviting us to notice that we would still find Fred’s actions objectionable. In other words, DDE, even when it is applied, will fail to justify Fred’s actions–according to Norcross.

What about the Warlord scenario back in W03? The short answer is that DDE doesn’t apply to the version of the scenario presented in W03. Since torturing the one villager is very much the means to save the rest, condition (c) fails–and the DDE, as formulated by its traditional (somewhat Deontological) proponents, don’t allow that. And given the Deontologist’s recognized duty in the scenario, condition (a) doesn’t hold either. This doesn’t mean an alternative versions of the scenario can’t be constructed where DDE applies–I’ll leave that to your own imagination. But the Deontologist won’t be helped by DDE in Warlord as presented in W03.

If you want to read more, check this out. Please understand that what’s behind the link is not only optional, it’s supererogatory!