EDIT: Mestroyer was the first one to find a bug that breaks this idea. Only took a couple of hours, that's ethics for you. :)
In the last Stupid Questions Thread, solipsist asked
Making a person and unmaking a person seem like utilitarian inverses, yet I don't think contraception is tantamount to murder. Why isn't making a person as good as killing a person is bad?
People raised valid points, such as ones about murder having generally bad effects on society, but most people probably have the intuition that murdering someone is bad even if the victim was a hermit whose death was never found out by anyone. It just occurred to me that the way to formalize this intuition would also solve more general problems with the way that the utility functions in utilitarianism (which I'll shorten to UFU from now on) behave.
Consider these commonly held intuitions:
- If a person is painlessly murdered and a new (equally happy) person is instantly created in their place, this is worse than if there was a single person who lived for the whole time.
- If a living person X is painlessly murdered at time T, then this is worse than if the X's parents had simply chosen not to have a child at time T-20, even though both acts would have resulted in X not existing at time T+1.
- If someone is physically dead, but not information-theoretically dead and a close enough replica of them can be constructed and brought back, then bringing them back is better than creating an entirely new person.
Or tl;dr: you are changing the utility function to fit it more closely to your experienced desires. Well, your utility function can be anything at all, it's "not up for grabs", as we say, which means that it is totally up for grabs by the person whose function it is.
But there's a meta-issue here. If you have a moral theory, whether utilitarianism of any sort or something else, and you find it yields conclusions that you find morally repugnant, from what standpoint can you resolve the conflict?
You can't just say "the theory says this, therefore it's right," because where did the theory come from? Neither can you say "my inner moral sense trumps the theory," or what was the theory for? Modus ponens versus modus tollens. When a theory derived from your intuitions has implications that contradict your intuitions, how do you resolve the conflict? Where can you stand, to do so?
As Socrates might ask a modern Euthyphro, "are the injunctions of your theory good because they follow from the theory, or do they follow from the theory because they are good?" In the first case, whence the theory? In the second, whence the good?
Personally I just take this as a bit of intellectual entertainment. It's fun to try to formalize moral intuitions and then look for the part where the formalization breaks, but that's it - I don't expect it to actually change anything about my behavior or anything like that.