 Another line appeals to the principle, often associated with Kant (1785), that “ought” implies “can” (OIC). You cannot be morally obligated to do something that’s impossible for you. While it would be good for you to eradicate world hunger, you are under no obligation to do so for the simple reason that you can’t. (You may, however, be obligated to relieve hunger to the extent you can.) Perhaps OIC is not, as Reid thought, “as self-evident as the axioms of mathematics” (Reid 1788: IV.v), but it is nevertheless very plausible.