Philosophical discussion of utilitarianism understandably focuses on its most controversial features: its rejection of deontic constraints and the "demandingness" of impartial maximizing. But in fact almost all of the important real-world implications of utilitarianism stem from a much weaker feature, one that I think probably ought to be shared by every sensible moral view. It's just the claim that it's really important to help others—however distant or different from us they may be.
As Peter Singer and other effective altruists have long argued, we're able to do extraordinary amounts of good for others very easily (e.g. just by donating 10% of our income to the most effective charities), and this is very much worth doing. (This doesn’t require dedicating oneself exclusively to promoting the good. You might have several other central life projects, while giving at least some substantial weight to the project of beneficence.)
It'd be helpful to have a snappy name for this view, which assigns (non-exclusive) central moral importance to beneficence. So let's coin the following:
Beneficentrism: The view that promoting the general welfare is deeply important, and should be amongst one’s central life projects.
Clearly, you don't have to be a utilitarian to accept beneficentrism. You could accept deontic constraints. You could accept any number of supplemental non-welfarist values (as long as they don't implausibly swamp the importance of welfare). You could accept any number of views about partiality and/or priority. You can reject 'maximizing' accounts of obligation in favour of views that leave room for supererogation. You just need to appreciate that the numbers count, such that immensely helping others is immensely important.
Once you accept this very basic claim, it seems that you should probably be pretty enthusiastic about effective altruism. Not making any claims about "obligation" here, but just in terms of basic warrant or fitting attitudes: we should care about what's important, and effective altruism basically just is the attempt to put beneficentrism into practice, i.e. to act upon what we've just agreed is deeply important. (Of course, you might have any number of empirical disagreements with other effective altruists about how best to achieve this goal. Nothing here commits you to agreeing with them about such details. I just mean that you ought to be enthusiastic about the basic project.)
Beneficentrism strikes me as impossible to deny while retaining basic moral decency. (Cf. Stalin's "a single death is a tragedy, a million deaths are a statistic.") Does anyone disagree? Devil's advocates are welcome to comment.
Even if theoretically very tame, beneficentrism strikes me as an immensely important claim in practice, just because most people don't really seem to treat promoting the general welfare as an especially important goal. Utilitarians do, of course, and are massively over-represented in the effective altruism movement as a result. But why don't more non-utilitarians give more weight to the importance of impartial beneficence? I don't understand it. (Comments welcome on this point, too.)
One possibility is that the standard ideology of "obligations", "permissions", etc., encourages people to focus on meeting the bare baseline of moral adequacy. (Didn't murder anyone today, hooray!) But I think that's a bad ideology. We shouldn't just care about avoiding wrongdoing. We should care about what's important.
So I'd like to invite everyone, whatever your moral-theoretical persuasion, to explicitly consider what you think is truly important, and whether beneficentrism might be a part of the answer.
And if you're then enthusiastic (as I hope you might be) about making beneficence a more central aspect of your life, maybe consider the Giving What We Can pledge, and/or other ways to make a difference?
Do you have an argument for beneficentrism, or just take it to be self-evident or intuitive? FWIW I would be inclined to accept some version of it, but that's based on various background moral commitments that motivate beneficence as a central moral principle. (E.g., I'm sympathetic to overlapping consensus as a moral methodology, and it aligns with my Christan faith, pace TonyZa's gloss)
"Beneficentrism strikes me as impossible to deny while retaining basic moral decency. Does anyone disagree? Devil's advocates are welcome to comment."
That depends on how you define basic moral decency or if you even believe that there is such a thing as a moral tenant that is universal.
But the truth is that most moral/religious/ideological systems in history didn't place much value on utilitarianism/beneficentrism. Ancient Greeks, Romans, Vikings and Mongols were not big on utilitarianism. Even Christianity, which puts a lot of weight on Works, is first concerned with Faith. Marxists might look utilitarian, but they see class struggle, the Revolution, and the accompanying blood shedding as taking priority with utopia happening only in the last phase. Nietzsche saw utilitarianism as the defining characteristic of a slave morality.