It might be objected that if morality demands too much—lacks options—then when people fall short of its requirements (as doubtless they will do) they will say to themselves that they might as well obey none of morality's requirements at all. Given this all-or-nothing attitude, it is important that morality's requirements not be too severe—for were they severe morality would fall into wide neglect, and this would clearly be less advantageous than if morality had been less demanding, and had its demands met. . . .
But I think we would be right to be sceptical of the claim that people have this all-or-nothing attitude. Many people disobey the speed limit; few consequently feel free to run down pedestrians. I see no reason why we couldn't teach people to think, ‘Well, I'm not doing all that I should—but only a monster would fail to do at least . . .’ Morality could continue to require the sacrifices while drawing various lines marking out different levels of moral offensiveness.
(Shelly Kagan, The Limits of Morality, Oxford Ethics Series, ed. Derek Parfit [Oxford: Clarendon Press, 1989], 35 [italics in original; first ellipsis added])
