What do you think of utilitarianism, as an ethical theory? Utilitarianism is the idea that the moral worth of an action is determined solely by it's usefulness in maximizing utility (or minimizing negative utility). Different utilitarian schools have different definitions of 'utility'. Peter Singer and many contemporary utilitarians are preference utilitarians, they believe that utility (or 'good') is the maximization of one's preference. Jeremy Bentham (a hero of mine) and the classical utilitarians were hedonists, they defined utility as happiness (Bentham did not make a distinction between 'lower' and 'higher' pleasures, all pleasures were equal in quality to him and differed only in terms of quantity, that is, intensity and duration). Most people claim to be opposed to utilitarianism despite the fact that they employ utilitarian reasoning in at least some scenarios (I won't get into why I've come around to the idea of 'net pleasure/pain'). I'm starting to think of myself as a (hedonistic) negative utilitarian. Let's say that you could measure happiness on a scale of 0 (neutral) to 100 (extreme, unimaginable happiness, no stress at all) and -100 would be extreme, unimaginable suffering, no happiness whatsoever. Let's say that John is at 50 and Bob is at -50, if given the option of increasing John's well- being by 30 points and increasing Bob's well- being by 20 points, a (positive)/classical utilitarian would give the 30 points to John, a negative utilitarian would give the 20 points to Bob. If given the alternate option of giving John 30 points or Bob 30 points, a positive utilitarian could go either way but neither would be morally preferable from a PU point of view (although the positive utilitarian might give the points to Bob out of personal compassion), a negative utilitarian will always give the points to the worse off person. I'm not denying that happiness is of intrinsic, positive value or that it is ethical (kind) to increase the happiness of already well off people but the first objective of morality should be to minimize unbearable suffering, minimizing suffering is morally urgent in a way that increasing happiness is not. The problem with NU taken to it's extreme conclusion is that it could justify blowing up the world if this could be done without causing any stress to sentient beings (or at least not any stress that wouldn't be outweighed by the stress that would continue to exist if you did not blow up the world). The problem with PU is that it could justify recreating the Holocaust if doing so caused a greater amount of happiness for more people than it would suffering for the victims. The worst conclusions of NU are still a lot better than the worst conclusions of PU since, in the apocalypse scenario, nobody would be around to regret the fact that they no longer exist and will never again experience happiness. It's better to be happy than it is to be unconscious (dead) but it's better to be unconscious than it is to suffer and, when you consider the worst suffering in the world (starving children, the agony experienced by people in the final stages of cancer or AIDS, watching your family members be raped and murdered, being burned alive etc.), blowing up the world warrants serious consideration. Preventing relatively happy people from experiencing future happiness is bad but nowhere near as bad as allowing the tragedy of extreme, long-term suffering to continue. Prioritarians also believe that it is more important to benefit worse off people than well off people, I'm not exactly sure where they differ from negative utilitarians.