Ask a hundred parents what they want for their children and most will say some version of "I just want them to be happy." Press a little further and the answer splits. Do they mean cheerful most days? Satisfied when they look back? Or living a life that is truly good for them, even if it includes hard stretches? Philosophers have argued over these questions for more than two thousand years, and psychologists and economists now try to measure the answers.
Two meanings of "happy"
The word happiness does double duty. In one sense it names a psychological state: feeling good, or being satisfied with how your life is going. In an older sense, the one translators use for the Greek word eudaimonia, happiness names a life that goes well for the person living it. Whether someone is happy in that sense is a judgment about their whole life, not their mood. A person can be cheerful and still, in the second sense, be living badly, for example if their cheer depends on a lie they have been told.
Philosophers today usually call the second idea well-being, or welfare, or a person's interest. Its kind of value is called prudential value: what is good for a particular person, as opposed to what is morally good or good in general. A kind act can be morally good while costing the one who does it. Prudential value is narrower: it asks what makes this particular life go better for the one who lives it.
Good in itself and good as a means
Most things we want, we want for the sake of something else. Money buys food and shelter; medicine restores health; a job pays the rent. Philosophers distinguish instrumental value, the value of a means, from intrinsic value, the value something has for its own sake. Theories of well-being try to say what is intrinsically good for a person. Money obviously matters, but almost no one thinks money is good for you in itself. A miser who hoards coins he never uses has mistaken a means for an end.
Three families of theory
In an appendix to his 1984 book Reasons and Persons, the British philosopher Derek Parfit sorted the main answers into three kinds: hedonistic theories, desire-fulfilment theories and objective list theories. The labels are still standard.
Hedonism says only pleasure is good for you in itself and only pain is bad. Desire theories say your life goes well to the extent that you get what you want. Objective list theories say certain things, such as friendship, knowledge and achievement, are good for you whether or not you enjoy them or want them.
A useful way to tell them apart is to ask how much each makes depend on the person's own mind. For the hedonist, well-being depends entirely on how your experiences feel. For the desire theorist, it depends on your attitudes, though those attitudes can be satisfied by facts outside your head. For the objective list theorist, some goods count even if you are indifferent to them. Philosophers call theories of the first two kinds subjective, because they tie well-being to the person's own feelings or attitudes, and the third kind objective.
Why the question matters
This can sound like a seminar puzzle, but it has practical edges. A doctor deciding whether to prolong a life, a government choosing what to measure, a parent pushing a child toward music lessons: each acts on some picture of what is good for a person. If well-being is just feeling good, a pill that produced lasting contentment would be a great gift. But if well-being includes knowing the truth or having real friends, the pill might leave something important missing.
The question also touches dignity and rights. If every person's life matters equally, then what goes well or badly in each life matters, and so does who gets to decide. A theory that lets officials overrule people's own judgments about their lives raises worries about paternalism. A theory that takes every preference at face value can miss real harm. Much of this subject is about steering between those two dangers.
Worked example: the contented clerk
Consider Daniel, a records clerk in his forties. He likes his routine, enjoys his evenings with crossword puzzles and the radio, and reports being satisfied with life. He has no close friends and has never traveled; when asked, he says he wants neither. Is Daniel's life going well for him?
A hedonist looks at his experiences. They are mostly pleasant and calm, so his life scores well. A desire theorist notes that he is getting what he wants, so again he scores well, unless his wants have been shaped by fear or a lack of chances. An objective list theorist may say he is missing goods like friendship, however content he feels. Already the three families pull apart on a real case.
Notice too the difference between the two senses of happy. Daniel is clearly happy in the psychological sense. The open question is whether he is happy in the fuller sense of a life going well, and that is a question his own report cannot settle by itself. Keep Daniel in mind; he will return.