 The preceding discussion takes for granted that an intuitive account of harm will be comparative in nature. On such an account, an act harms a person only if that act makes that person worse off than he or she would have been under an alternative act; a person p is not harmed at a given world w unless there exists some alternate world w′ such that p has more wellbeing at w′ than p has at w; an act that maximizes wellbeing for a person at a world w cannot harm that person at w. At least: it cannot do so in any “morally relevant sense” (Parfit 1987, 374). 