This dissertation in Theory of Practical Knowledge contends that depression is a disorder of the self. Using the existential-phenomenology of Maurice Merleau-Ponty, I argue that if we want to disclose the basic structure of depressed experience, then we must likewise disclose how selfexperience is inseparable from depressed experience. However, even though depression is a contemporary psychiatric category of illness, it is nevertheless a historically and heterogenous concept. To make sense of depression in the context of contemporary psychiatric practice, I show (...) that depression has historically been characterized by two broad models of causation; that is, a phenomenon that is causally explained by either a biological dysfunction or a psychological conflict. But this stark characterization is not limited just to history; by conducting qualitative interviews with psychiatric professionals, I illustrate how this causal dichotomy remains prevalent in contemporary psychiatric practice. On one hand, the clinicians report dissatisfaction with the depression diagnostic criteria (i.e. it is impersonal or vague), while on the other hand, the clinicians also recognize that a depression diagnosis is useful insofar as a diagnosis facilitates access to various resources associated with psychiatric care. Consequently, clinicians have developed a coping strategy that is witnessed in their empathetic desire to distance patients from their depression diagnosis, which led to statements such as, “you are not the problem, the problem is depression.” One consequence of this approach is that depression is artificially cleaved from the person who experiences depression, which subsequently means that depression is viewed to be something independent of oneself. Because I argue that depression and the self are mutually implicated, it is crucial to disseminate some of the most influential contemporary models of selfhood. I show that the brainbound, situated, psychological, and narrative model of self, all have respective strengths and weaknesses. But I also go beyond these models and characterize selfhood as a developmental phenomenon that is expressed as an embodied-style. This style reflects the way in which we establish perceptual contact with the otherness, without which there could be no self-experience. (shrink)