Historically, philosophers have identified happiness with, among other things, pleasure, contentment, desire satisfaction, and, if we count the Greek eudaimonia as happiness, the life of virtue. When faced with competing theories of happiness, we need a way to decide which theory is more accurate. According to Larry Wayne Sumner's principle of descriptive adequacy, the best theory of happiness is the theory that best describes our ordinary, pretheoretical beliefs and intuitions. The chief aim of this article is to show that the principle of descriptive adequacy is mistaken. To do this, it shows how the principle breaks down when applied to Aristotle's theory of eudaimonia, a theory Sumner claims to be descriptively inadequate as a theory of happiness. The article argues that we should reject descriptive adequacy as a metaphilosophical principle on the grounds that our intuitions and beliefs about happiness are too inchoate for any theory adequately to describe.