Quality of Life

Parfit's Three Theories

The different answers to this question can be classified in somewhat different ways. Most of the modern discussion of well-being is based on Derek Parfit's distinction between three kinds of conceptions of the good life, namely, hedonistic theories, desire-fulfillment theories, and objective list theories.

On the hedonistic theory, the good life is identical with the pleasant life. The only thing that has positive final value for a person is pleasant experience (to feel good), and the only thing that has negative final value for a person is to feel bad. The prudential value of a life is a function of how much pleasure and displeasure it contains.

According to the desire-fulfillment theory (desire theory, preferentialism), someone has a good life only if she has the kind of life that she herself wants to have. The only thing that has positive final value for a person is that her intrinsic desires are fulfilled, and the only thing that has negative final value for a person is that her intrinsic aversions are fulfilled, that she gets what she does not want. The desire theory is commonly regarded as a formal rather than a substantive theory of well-being. Instead of making substantive claims about what is good for us, it specifies a formal criterion that helps us determine what is good for us, namely, that something has final value for a person if and only if (and because) she desires it intrinsically, as an end. (It is worth noting that even though hedonism is almost always regarded as a substantive theory, it has also been conceived of as formal, e.g., by various economists. On the formal interpretation of hedonism, prudential value is not attributed to the [Page 1186]pleasant experiences themselves but to the different objects in which the subject takes pleasure.)

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