 “[P]ractised self-consciousness and self-observation, assisted by observation of others” reveals that human beings do, as a matter of fact, desire happiness (Utilitarianism, X: 237). We do so, Mill claims, by virtue of our nature—and that propensity strikes us as reasonable upon inspection. That human beings universally do desire happiness, and take it to be reasonable to do so under free consideration, is evidence that happiness is desirable. Such evidence, of course, is defeasible—but real nonetheless. And in the absence of reasons to doubt our universal tendency to desire happiness, we are warranted in taking happiness to be desirable. The argument for the desirability of happiness is, in this sense, parallel to Mill’s initiating validation of the principle of enumerative induction (see  §3.2).