Utility monster

The utility monster is a thought experiment in the study of ethics created by philosopher Robert Nozick in 1974 as a criticism of utilitarianism.

A hypothetical being, which Nozick calls the utility monster, receives much more utility from each unit of a resource they consume than anyone else does. For instance, eating a cookie might bring only one unit of pleasure to an ordinary person but could bring 100 units of pleasure to a utility monster. If the utility monster can get so much pleasure from each unit of resources, it follows from utilitarianism that the distribution of resources should acknowledge this. If the utility monster existed, it would justify the mistreatment and perhaps annihilation of everyone else, according to the mandates of utilitarianism, because, for the utility monster, the pleasure they receive outweighs the suffering they may cause. Nozick writes:

Utilitarian theory is embarrassed by the possibility of utility monsters who get enormously greater sums of utility from any sacrifice of others than these others lose ... the theory seems to require that we all be sacrificed in the monster's maw, in order to increase total utility.

This thought experiment attempts to show that utilitarianism is not actually egalitarian, even though it appears to be at first glance.

The experiment contends that there is no way of aggregating utility which can circumvent the conclusion that all units should be given to a utility monster, because every different system has a monster and defeating one utility monster creates another. For example, in Rawls' maximin or difference principle, maximin sets a group's aggregate utility as that of the being with least utility. Thus, giving units to the utility monster fails to change the group's utility unless the utility monster has the least utility. Even if the utility monster has the least utility, maximin would only prefer allocating units to the monster until it catches up with the member that has next-to-least utility. This would defeat the "happy" utility monster of average utility. But if the person who has the least utility gains only a tiny amount of utility from each unit of resources, they may never catch up with the next person, so they can similarly consume all of the resources in the world. It can be shown that all consequentialist systems based on maximizing a global function are subject to utility monsters.

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