But you can’t measure it and you can’t add it, so you have no way of knowing whether any particular act is increasing it or decreasing it - how can you maximize it?
How do you know?
So, if allowing every male to rape Angelina Jolie maximizes social utility, we are supposed to tramp natural rights? If simply killing everyone that steals makes a better society, we are supposed to agree with it? If enslaving 1/3rd of the population makes the majority happy, then you are for it? The list goes on and on.
Hence the problem of utilitarianism.
Prosperity and utility maximization for that mythical entity referred to by “the people” must never be the goal of public policy. It is the root of all evil in the context of societal organization. It’s sadistic, and inherently violent and murderous. Anyone advocating such a goal is declaring himself a threat to all human beings. Anyone who claims it doesn’t require violence is delusional and psychotic, and thus doubly dangerous.
Utility maximization for “the people” would demand the immediate extermination of such people, so it’s probably a good thing I don’t believe in it.
The flaw is in thinking they are in opposition. If you were to perfectly follow the goal of maximization of utility, the means you would choose would be complete freedom from aggressive violence, the NAP. But you can’t perfectly pursue it, because you can’t measure it. The choices are: don’t pursue it because doing so is nonsensical, or pursuing it using the requisite violence needed to distort reality enough to allow the pretense of such a pursuit.