We can argue that John Stuart Mill’s idea of utilitarianism would not make the world a better place because it would encourage behavior that is both immoral and unfair to some people.
Mill’s philosophy of utilitarianism is a consequentialist view of what people should do. That means that it bases its notions of right and wrong on the results of people’s actions, not on their motives or on how well they conform to moral laws. Utilitarianism holds that people should act in ways that will create the greatest happiness for the greatest number of people. If all people in the world acted in this way, the world would surely be a terrible place.
Imagine, for example, a situation in which a very popular celebrity needed an organ transplant. If the person were to be saved, millions would be overjoyed. Now imagine that we could get an organ to transplant into the celebrity by killing a person who has no family or friends and is unimportant. Surely, killing the person would add to the overall happiness experienced by people in our society. However, this would be terribly immoral and unfair to the obscure person. A society that allowed such actions would be horrible.
For reasons like these, Mill’s ideas, if carried out in the real world, would not make the world a better place.