In utilitarianism what is a "utility monster," and what is the general concern that the idea of the utility monster brings to light?

Classical utilitarianism as a philosophy was introduced by Jeremy Bentham in An Introduction of the Principles of Morals and Legislation, published in 1789.  The theory contends that the best moral avenue is the one that results in the most pleasure for a society, and therefore the least pain.  In this way utilitarianism is a type of consequentialism, judging actions by their consequences rather than their isolated identity.  This resultant satisfaction in individuals from a...

Classical utilitarianism as a philosophy was introduced by Jeremy Bentham in An Introduction of the Principles of Morals and Legislation, published in 1789.  The theory contends that the best moral avenue is the one that results in the most pleasure for a society, and therefore the least pain.  In this way utilitarianism is a type of consequentialism, judging actions by their consequences rather than their isolated identity.  This resultant satisfaction in individuals from a moral or legislative action is referred to as utility.  So, utilitarianism believes that the most correct action in any situation is that which results in maximum utility after factoring in the degree of suffering involved in the action.

The utility monster was proposed by Robert Nozick in 1974 as an ethical challenge to utilitarianism.  Utilitarianism claims to be an egalitarian philosophy, and yet Nozick introduced this hypothetical monster, who produces vastly greater quantities of utility than other individuals from consuming the same resources.  In other words, for this being there are no diminishing returns on happiness; its utility grows and grows the more it consumes, and therefore its net happiness outweighs the happiness of the rest of society.  Even if the rest of the hypothetical society were suffering vastly, this utility monster’s huge quantity of pleasure would give the society a net gain in happiness.  In this scenario, utilitarianism’s egalitarian nature breaks down, and its core philosophy gets flipped on its head to benefit the least amount of people at the expense of the others.

The utility monster today remains, of course, just a thought experiment, and there have been no examples of a single organism’s exponential degree of happiness cancelling out any large degree of pain suffered by a majority within a society.

Saturday Morning Breakfast Cereal has a good web comic that perfectly illustrates the basic concept and problems that would arise from the existence of a utility monster.