Morality in government

Zachriel asserts that hospitals have a moral obligation to treat all patients who come through their door (or at least those with serious problems, I’m not sure which).  He appears to feel, though he has not asserted it quite this way, that government has some sort of moral obligation to provide a more “egalitarian” society, whatever that means (I would argue, for example, that a progressive tax in not egalitarian, only a flat tax is, and I suspect he’d disagree). 

On the other hand, I have asserted and believe that a government spending beyond its means and leaving the bill for our children to pay is immoral.  My question is, how do we measure morality in government?  We can certainly discuss, as we have been, what is best for government to do, what kind of government results in the best society (whatever best means), and other utilitarian concerns.  But I think the most fundamental difference between the left and the right is not over utility, but over morality.  

For example, the right believes that a government that steals from the rich, and the middle class and pretty much everyone else, including future generations to give to the poor (wherther or not the poor have done anything to help themselves) is immoral.  The left believes that a government that does not help the poor (simply because they are poor) and does not strive for a more egalitarian society and some abstract idea of fairness is immoral.

This introduces two levels of questions.  First, what do each of us think are the moral limitations on a government?  To continue the above focus, for example, is there such a thing as an immoral level of taxation?  Does the morality of a tax depend on the level of income (a 75% tax on millionaires would be okay, but a 75% tax on the poor would be immoral) or on fairness (flat tax versus progressive)?

Second, how do we resolve differences over what a moral government should and can do?  How do we even talk about the issue without talking past each other?