I think the problem with charity reflects an ethical question: what exactly does it mean that something is "good", and if something is "good" what should be the consequences for our behavior?
The traditional answer is that it is proper to reward doing "good" things socially, but they should not be enforced legally. One will be celebrated as a hero for saving people from a burning house, but one will not be charged with murder for not saving people from a burning house.
On the other hand, doing "bad" things should be punished not only socially but also legally. Stealing things from others is punished not only by losing friends, but also by prison.
What is the source of this asymetry? Why is "bad" not the opposite of "good", with all consequences? This is especially important for utilitarians, because if we convert everything to utilons, at the end we have a choice between an action A which creates a worldstate with X utilons, and B which creates the worldstate with Y utilons. Knowing that X is greater than Y, should we treat action A as "good", or action B as "bad"?
My guess is that we have some baseline that we consider the standard behavior. (Minding your own business, neither helping others nor harming them.) A "good" action is change from this baseline towards more utilons, a "bad" action is change from this baseline towards less utilons. Not lowering this baseline is considered more important than increasing it. It makes sense to have a long-term Schelling point.
Problem is that if you change this baseline, you have redefined the boundary between "good" and "bad". And people disagree about where exactly should this baseline be. If two groups disagree about the baseline, they have moral disagreement even if they use the same utility function. They disagree about whether choosing worse B instead of better A should be punished.
For example people are socially rewarded for giving money to charity, but they are not punished for not giving to charity, because the baseline is "not giving to charity". On the other hand, people are punished for not paying taxes, because the baseline is "paying taxes". Both concepts mean "giving up personal money to improve the society", but the reactions are different, because the baseline is different.
Giving money to poor people creates some utility, and the question is: where is the baseline? For some people the baseline is "keeping what you have" or "keeping most of what you have, but not all, especially if you have more than your neighbors". For socialists the baseline is "doing the best thing possible", because this makes sense for a utilitarian. I guess, for a socialist, voluntary charity is a textbook example of compartmentalization. ("If you think giving money to poor people is the right thing to do, because it creates utility, what not make it a law for everyone, and create a lot more utility? And why not give as much as possible, to create as much as possible utility?") For a non-socialist, this kind of thinking seems like a huge conjunction fallacy, and also while we value the well-being of others, we usually value our own well-being more, so it makes sense to contribute only to the most urgent causes.
The traditional answer is that it is proper to reward doing "good" things socially, but they should not be enforced legally. One will be celebrated as a hero for saving people from a burning house, but one will not be charged with murder for not saving people from a burning house.
You're conflating two different questions here:
What interval of quantified goodness (utility) should the Law actively promote, by distributing punishments or rewards to agents? What are the least good good deeds the Law should care about, and what are the most good
The current issue of the Oxford Left Review has a debate between socialist Pete Mills and two 80,000 hours people, Ben Todd and Sebastian Farquhar: The Ethical Careers Debate, p4-9. I'm interested in it because I want to understand why people object to the ideas of 80,000 hours. A paraphrasing:
As a socialist, Mills really doesn't like the argument that the best way to help the world's poor is probably to work in heavily capitalist industries. He seems to be avoiding engaging with Todd and Farquhar's arguments, especially replaceability. He also really doesn't like looking at things in terms of numbers, I think because numbers suggest certainty. When I calculate that in 50 years of giving away $40K a year you save 1000 lives at $2K each, that's not saying the number is exactly 1000. It's saying 1000 is my best guess, and unless I can come up with a better guess it's the estimate I should use when choosing between this career path and other ones. He also doesn't seem to understand prediction and probability: "every revolution is impossible, until it is inevitable" may be how it feels for those living under an oppressive regime but it's not our best probability estimate. [1]
In a previous discussion a friend also was mislead calculations. When I said "one can avert infant deaths for about $500 each" their response was "What do they do with the 500 dollars? That doesn't seem to make sense. Do they give the infant a $500 anti-death pill? How do you know it really takes a constant stream of $500 for each infant?". Have other people run into this? Bad calculations also tend to be distributed widely, with people saying things like "one pint of blood can save up to three lives" when the expected marginal lives saved is actually tiny. Maybe we should focus less on estimates of effectiveness in smart-giving advocacy? Is there a way to show the huge difference in effect between the best charities and most charities without using these?
Maybe I should have way more of these discussions, enough that I can collect statistics on what arguments and examples work and which don't.
(I also posted this on my blog)
[1] Which is not to say you can't have big jumps in probability estimates. I could put the chance of revolution at 5% somewhere based on historical data but then hear some new information about how one has just started and sounds really promising which bumps my estimate up to 70%. But expected value calculations for jobs can work with numbers like these, it's just "impossible" and "inevitable" that break estimates.