Very plausibly, there is something important missing in our lives if we are thoroughly ignorant or misled about reality – even if, as in a kind of Truman Show scenario, intervention or fantastic luck prevents unhappiness and practical failure. But why? I argue that perfectionism about well-being offers the most promising explanation. My version says, roughly, that we flourish when we exercise our self-defining capacities successfully according to their constitutive standards. One of these self-defining capacities, or capacities whose exercise reveals (...) who we are, is Reason, our capacity for normative self-governance. I argue that in its practical use, Reason formally aims at competently realizing self-chosen valuable ends that are in harmony with each other, or valuable achievements. In its theoretical use, it formally aims at competently grasping fundamental enough subject matters, or a kind of understanding. Because success by reason’s own standards requires many things to go right, there are many different ways in which we can fall short. Some of them amount to partial success. But some, like incompetent inquiry that fails to yield understanding of its target, or taking inefficient means to a worthless end, are robust failures that amount to epistemic or agential unflourishing, and thus to a form of ill-being. (shrink)