Hyperreflexivity, understood as intensified self-consciousness in which subjects disengage from normal forms of involvement with nature and society, often considering themselves as objects of focal awareness, is proposed here as a condition of mental disorders, without which they would not exist. This thesis is argued from a dual perspective: clinical and historical. In the clinical perspective, it is shown that hyperreflexivity is not merely concomitant with mental disorders, but indeed has causal priority over them. Empirical evidence of a correlational, experimental and therapeutic nature, or deriving from cultural change, supports this claim of causal priority. In the historical perspective, it is shown that hyperreflexivity depends on certain historical-cultural circumstances that have prevailed since the Renaissance. These circumstances have to do with the emergence of the modern subject, displaced, autonomous and condemned to a hapless 'interior journey'. This means that mental disorders as such would not have existed prior to that era. Nor in the wake of the Renaissance would mental disorders automatically come into being, depending as they do on a reflexive, institutional clinical context, which would not emerge until practically the nineteenth century, but which would extend swiftly from then on.