Bentham's Principles can be divided into three parts: (1) his view on what motivated human beings; (2) an explanation of the principle of utility; (3) and an account of his felicific, or happiness, calculus.

Bentham found pleasure and pain to be the sole motivators and only absolutes in the world. He opens his Principles thus:

Nature has put man under the governance of two sovereign masters: pain and pleasure. It is for them alone to point out what we ought to do, as well as to determine what we shall do. On the one hand, the standard of right and wrong, on the other the chain of causes and effects, are fastened to their throne. They govern us in all we do, in all we say, in all we think: every effort we can make to throw off our subjection, will serve but to demonstrate and confirm it. In words a man may pretend to abjure their empire: but in reality he will remain subject to it all the while.

Bentham gives his account of what motivates human beings. As with previous psychological hedonists like Epicurus, Bentham claims that human beings are under the spell of the twin “sovereign masters” pleasure and pain. People will move toward objects and activities they find pleasurable and shun those they find painful. There is possibility for reform, however. If a person finds study to be painful, he will need to have his behavior reformed so that he can take pleasure in it. Perhaps the reward of learning new things or the satisfaction of getting an A on a test will lead him to find learning pleasurable.

Utility and Value

From Bentham's view of pleasure and pain he derived his rule of utility: that the good is whatever brings about the greatest happiness. Utilitarianism, then, is a teleological moral theory, the goal of which is to produce the greatest amount of net utility (pleasure minus pain) where utility is defined in terms of happiness or pleasure. Thus, if it is within your power to bring about equal amounts of happiness in three people or in two people, you should bring about that happiness in three rather than two.

In general, goodness or value is defined in terms of utility. Utility, in turn, is defined in terms of how much pleasure is produced. With Bentham's philosophy you could analyze topics as diverse as the ethics of warfare, mercy killing, abortion, and other matters of applied ethics. A war could be judged by whether it produced more long-term pleasure or pain. The principle of utility analyzes results but overlooks motives, for as John Stuart Mill, Bentham's successor in utilitarianism said, “He who saves as a fellow creature from drowning does what is morally right, whether his motive be duty or the hope of being paid for his trouble.” So in the motive-act-consequence schema, it is the last that counts the most.

The Happiness Calculus

For utilitarians an action is right if and only if there is no other act the agent could have done instead that has higher utility than it has. But how is this higher utility calculated? Bentham actually had a way of calculating pleasures and pains. In fact, he asserted that there are seven factors that help you measure pleasures and enable you to make the calculation.

Since he had social reform at heart, Bentham thought that legislators ought to improve society by increasing general pleasure and decreasing the pain of its citizens. “Pleasures and the avoidance of pains are the ends which the legislator has in view,” Bentham wrote in the Principles. The seven “pleasure” factors are intensity, duration, certainty or uncertainty, propinquity or remoteness, fecundity, purity, and extent.

Intensity refers to how strong the pleasure is. Duration refers to how long it lasts. Certainty or uncertainty refers to whether the pleasure will occur or not. Propinquity or remoteness refers to whether the pleasure is near at hand or far away. Fecundity refers to whether the pleasure or pain will be followed by similar sensations. Purity (the opposite of fecundity) is the chance of its not being followed by sensations of the opposite kind. Finally, extent refers to the number of persons affected by the action.

These are the components that make up the “hedonic calculus.” How does it apply to actual practice? Bentham offered an answer. Suppose you are contemplating which action to do — study for a final exam that is two days away or attend a campus party on one of the nights before the exam. How would you analyze what to do? “Sum up all the values of the pleasures on one side, and those of all the pains on the other side,” Bentham says. A person reviewing these choices finds the intensity of the pleasures promised by the party alluring. Meanwhile, studying for a final exam promises only a low-intensity pleasure. The person now adds the factor of duration and sees that the pleasures of eating and drinking and socializing at the party are relatively brief. By contrast, studying may produce long-term pleasurable consequences, especially if the student is able to perform well on the test, improve his grade point average, increase his chances of getting the job he wants, or getting into law school, med school, graduate school, and so on. He also sees that the purity of the party pleasure is low, since if he drinks excessively he may have a hangover the following day. So pleasure is followed by pain, whereas studying produces no such pain — aside perhaps from possible minor discomfort to one's eyes or backaches from sitting up straight.

The person may include in his calculation certainty and uncertainty, propinquity and remoteness, fecundity, and extent. But the result of Bentham's “hedonic calculus” in this and other cases is clear. The lasting pleasures all fall on the side of the mental pleasure of studying; partying, by contrast, includes only short-term pleasures. One might reply, however, that the person attending the party will meet the love of her life and so the party pleasure may turn out to have greater duration. Following Bentham, our student would sacrifice going to the party to put in the necessary hours studying.