Take into account how long the pleasure will last, how intense it is, how likely it is that it will give rise to further pleasures. Then subtract any units of pain that might be caused by your action. What you are left with is the happiness value of the action. Bentham called this its ‘utility’, meaning usefulness, because the more pleasure an action brings about the more useful it is to society. That's why the theory is known as utilitarianism.
