Many moral philosophies seem to imply a duty to give away everything you don't need. Consider this statement by Nicole Hassoun over at Cato Unbound:
I do not have property rights that extend so far that they allow me to
withhold essential goods that I do not need from those who will suffer
and die without them.
In a follow-up, though, Hassoun denied that this commits her to the view that she has a moral duty to give away all her surplus wealth:
[W]hile I think that the current distribution of property rights globally
is very unjust because it leaves people unable to meet their basic
needs, I do not believe the best way of addressing the problem is
through individual action.
I beg to differ. Given some highly probable empirical assumptions, Hassoun's position does indeed require her to donate all her surplus wealth to the global poor. In my latest post, I spell out the argument:
1. Hassoun does not have property rights that extend so far that
they allow her to withhold essential goods that she does not need from
those who will suffer and die without them. [Hassoun's original premise,
with "Hassoun" instead of "I."]
2. People in the Third World are now suffering and dying due to lack of essential goods. [Certainly a true empirical claim.]
3. Third World suffering and dying will persist even if Hassoun takes all actions in her power other than
massive personal financial donation, such as voting, political
activism, blogging, and teaching. [An extremely probable empirical
claim, given that Hassoun is only one person in a world of seven
4. Hassoun has essential goods (namely money) that she does not need.
[An extremely probable empirical claim, given that she works as a
professor in the First World, and First World professors earn far more
5. People in the Third World will suffer and die if Hassoun withholds
these essential goods. [An extremely probable empirical claim, given
the existence of dire poverty and effective international charities.]
6. Therefore, Hassoun does not have property rights that allow her to
withhold essential goods she does not need. In plain English, she has a
moral obligation to donate all her surplus wealth to people in dire
poverty. [From #1-#5.]
Of course, dire poverty will persist even if Hassoun does
donate all the wealth she does not need. But her principle does not
require her to end world poverty. It merely requires her to give away
everything she does not need until dire poverty no longer exists.
While we're on this topic, can't you use the same kind of logic to argue that every libertarian who works for the government should resign? It depends. If the libertarian's view is something like, "Every government employee is guilty of robbery," then sure. But a libertarian could easily claim that the only a narrow subset of government employees (e.g. tax collectors, judges who try tax cases, and politicians who vote for taxes) are guilty of robbery. Other government employees might even legitimately claim that they're victims recovering a fraction of the damages the government owes them for past and ongoing wrongs.