Are We Conditionally Obligated to be Effective Altruists?

It seems that you can be in a position to rescue people in mortal danger and yet have no obligation to do so, because of the sacrifice to you that this would involve. At the same time, if you do save anyone, then you must not leave anyone to die whom it would cost you no additional sacrifice to save. On the basis of these claims, Theron Pummer and Joe Horton have recently defended a ‘conditional obligation of effective altruism’, which requires one to give to the most cost-effective charity if one is going to make a charitable donation at all, all other things equal. Appealing to a distinction between 'thoroughgoing' and 'half-hearted' non-consequentialism, I argue that their inferences don’t go through, and moreover that this sort of argument in general is unlikely to work as a way to defend effective altruism.