The simplest theory of well-being is also one of the oldest. Hedonism about well-being holds that pleasure is the only thing good for you in itself, and pain the only thing bad. Everything else, from friendship to money to health, matters only because of the pleasure it brings or the pain it prevents. The word comes from the Greek hedone, pleasure.

Bentham's arithmetic

The English reformer Jeremy Bentham gave hedonism its most famous modern form. His Introduction to the Principles of Morals and Legislation, printed in 1780 and published in 1789, opens: "Nature has placed mankind under the governance of two sovereign masters, pain and pleasure." Bentham thought pleasures differ only in amount, and he listed the dimensions along which amount can be measured, including intensity, duration, certainty and nearness in time, plus how likely a pleasure is to lead to more pleasure and how many people it reaches. Later writers called his method the felicific calculus.

Bentham's view had a radical, democratic edge. If pleasure is pleasure, then no one's enjoyments count for more because of their rank, and a laborer's pain counts exactly as much as a lord's. He even suggested that, setting prejudice aside, a simple pub game was as valuable as poetry if it gave as much pleasure.

Mill's higher pleasures

John Stuart Mill, raised by his father to be Bentham's heir, accepted that pleasure is the good but rejected the idea that only quantity matters. In Utilitarianism (1863), he answered critics who called the view a doctrine worthy only of swine. Humans, he replied, have faculties of intellect, feeling and imagination, and the pleasures of using them are of a higher kind. To decide which of two pleasures is higher, Mill appealed to people who have experienced both: if nearly all who know both prefer one, even at the cost of some discomfort, it is the higher. Hence his famous line: "It is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied."

Critics have asked whether Mill can keep both claims. If one pleasure is better than another without being more pleasant, then something other than pleasantness is making it better, and the view is no longer pure hedonism. Defenders reply that a richer pleasure is simply a greater one.

The experience machine

The best known objection to hedonism came from the American philosopher Robert Nozick in Anarchy, State, and Utopia (1974). Imagine, he said, a machine that could give you any experiences you wanted. You would float in a tank while it made you feel you were writing a great novel or falling in love. Would you plug in for life?

Nozick expected most people to refuse, and he offered three reasons, here in paraphrase. We want to actually do certain things, not merely have the experience of doing them. We want to be a certain kind of person, and someone floating in a tank is hardly any kind of person at all. And plugging in would shut us inside a world built by others, cut off from any reality deeper than what people can construct. If anything matters to us besides how our lives feel from the inside, Nozick concluded, then hedonism is false.

Replies and doubts

Hedonists have not given up. Some argue that our refusal reflects fear, distrust of the technology or attachment to the familiar rather than a real insight about value. In a 2010 study, the philosopher Felipe De Brigard turned the case around. When people were told they were already in such a machine and could unplug to return to a real life, many chose to stay plugged in, especially when that real life was described as unpleasant. That suggests a status quo bias: people tend to prefer whatever they have now. Still, many philosophers think the machine shows something true.

Hedonism keeps one great strength: it explains why well-being matters to the person. It is hard to see how something could be good for you if it never made any difference to how your life felt. Philosophers call this the experience requirement: nothing can make your life better or worse unless it affects your experience. The experience machine is a test of whether you accept it.

Worked example: the deceived spouse

Imagine two lives that feel identical from the inside. In both, Rosa is happily married for forty years, raises children and dies content. In the first, her husband is faithful. In the second, he deceives her throughout, with such skill that she never suspects. A strict hedonist must say the two lives were equally good for Rosa, since her experiences were the same.

Most people find that hard to accept. The second life seems worse for her, even though she never knew. That intuition is the experience machine in everyday form, and it is a direct challenge to the experience requirement. A hedonist can bite the bullet, saying that our discomfort tracks the moral wrong done by the husband, not any loss in Rosa's own well-being. Whether that reply convinces you is a good test of your own view.