Another passage by Matt Zwolinski on poverty and desert that keeps coming back to me:

[A]ny measures we take to diminish the likelihood of false positives –
people getting welfare who don’t deserve it – will probably increase
the likelihood of false negatives – people not getting welfare who
should.  Most plausible systems of morality, I should think, will hold
the latter consequence to be much more troubling than the former.

This sounds really good.  But no one lives up to this standard unless they’re spending someone else’s money.  Every time you fail to help a beggar on the grounds that “He’ll probably just spend it on alcohol,” you’re risking a false negative.  And did you take a minute to talk to the beggar to improve the accuracy of your judgment?  <sarcasm>Yea, right.</sarcasm>

You could respond, of course, that we’ll all a bunch of sinners, willfully shirking our duties to the overlooked deserving poor.  You might insist that we should worry a lot more about false negatives – and try a lot harder to avoid them – than we do.  But when you really picture what’s involved – chatting with every hard-luck case you pass, and giving unless you’ve got solid evidence that they’re not deserving – you need no libertarian sympathies to see the absurdity.

An alternate response is that governments should be morally risk-averse even though individuals aren’t.  But it’s hard to see why.  If you wouldn’t condemn an individual donor for accidentally failing to help the deserving poor, why would you condemn his government for a comparable error rate?

Last point: Suppose you think I’m underrating the moral evil of false negatives.  As I argued earlier, forcing people like me to pay extra taxes to address this evil is still hard to defend:

[I]f you think reasonable people could disagree here, it’s an argument against forced charity.  There’s always a presumption against
initiating the use of force against a peaceful person.  “Any morally
reasonable person would agree that I’m forcing you to help the
deserving poor” at least arguably overcomes this presumption.  “Who
knows whether the people I’m forcing you to help are deserving?” does