I suggested this division of causes because, first, people who earn to give may join the upper or at least upper middle class. It seems harder to advocate for things like socialism when your peer group is rich. Your opinions aren't going to earn you praise or friends and friends and connections are really important for making money. It's also hard to devote time and energy to maintaining odd views when you're focused on a career that isn't directly involved with acting on those opinions. You're losing some potential synergy. It also possible that, second, the usefulness of cash donations varies with whether the cause has support among the rich or poor, although this might work the other way in that I would expect causes that favor the poor to need money more.

But with a topic like abortion this all seems unclear--although opinions on abortion do correlate some with income, I don't think that correlation is a strong as with outright economic redistribution. What do you think?

If you want to suggest a more clearly neutral topic than abortion I would be interested to hear it.