The requirements of double effect are as follows:
- the nature of the act is itself good, or at least morally neutral;
- the agent intends the good effect and not the bad either as a means to the good or as an end itself;
- the good effect outweighs the bad effect in circumstances sufficiently grave to justify causing the bad effect and the agent exercises due diligence to minimize the harm
We cans see how this meets the requirements of double effect:
1.) Taking the promotion is, itself a morally neutral act.
2.) The primary income earner means well when taking the promotion and moving his/her family across the country.
3.) The primary income earner determines that the good of the move will outweigh the negatives, even if this means a strained relationship with Billy. He or She tries to make it up to Billy by spending more time with him, but for the most part Billy is still resentful.
Under double effect, the primary income earner would have no responsibility, regarding Billy's hurt feelings, even though he/she knew in advance that this would harm their relationship.
As I see it, the problem with double effect is that it absolves a person from the moral harm of a foreseen consequence of an action. This would be no problem with a Utilitarian ethic, but as Catholics like to point out maximizing pleasure and minimizing harm is an insufficient form of moral reasoning. "One can't do evil, so that good will occur," is a common refrain in Catholic circles. Double-effect, in practice, can look very much like utilitarianism.*
Using double effect reasoning, a woman with an ectopic pregnancy can have her fallopian tube and fetus surgically removed, while remaining innocent of the sin of abortion. In this case, the intention is to remove the troublesome fallopian tube, not have an abortion. The removed fetus is an unintended and unfortunately necessary consequence of accomplishing the primary intention (removing the fallopian tube).
Once again I see the reasoning as insuffient. Although a consequence may be sad or unintended, if you fully know something bad will happen as a result of an action, committing that action anyway, is in some way still intending for the bad to occur.** Just because I don't like the consequences of my action, doesn't mean I'm not responsible for those consequences, when I have a reasonable knowledge of my action's outcomes.
Logically, double effect makes little sense.
* I, personally, have no problems with Utilitarian moral reasoning in these situations.
** I am not saying that woman aborting a fetus for medical reasons commits a moral wrong. I'm simply using this example to point out the absurdity of double-effect logic and why such silly logic is necessary when one holds an absolutist view on abortion.