- These people tend to have no hesitation about whether such a thing is possible. Granted, a sensible "progressive" argument may be made, but I get the sense that people like Chris Matthews (whose proclamations about the government's moral obligations toward the poor tonight prompted this post) have no notion that moral agency is delimited where the scarcities and limitations posed by reality encroach. I may say that the government has a moral obligation to end poverty once and for all, but that doesn't make it so. Similarly, Chris Matthews may say that the government has a moral obligation to create an atmosphere on Mars, but saying so doesn't make it so.
- Institutions like governments don't participate in "morality" as I understand it; only individuals can be morally responsible. The rest is a matter for the pragmatists.
Regarding the second point: I'm more and more convinced that people use this kind of rhetoric in order to justify, to themselves, their own felt-but-not-consciously-recognized knowledge that they have arbitrarily limited their own circle of moral sympathy.