Traditional art theory, stating that artists represent their societies, is less supported since modern art emerged. Especially because insane behaviors and isolated attitudes in the modern artists have been obserbed, as long as they think the subject in mimesis demands the ability to recognize and grab their world's essence, the insane have been regarded as the lack of the reason. Thus irrational aspects in modern arts don't look to fit the mimesis theory any more. This article, however, attempts to overcome the ideological and dogmatic approaches in mimesis and to reinterpret it in relation to the discourses of Freud, Foucault and Merleau-Ponty about insanity. Likewise, the Cartesian cogito and conception of doubt need to be reanalyzed as intermediate in the process of reaching this goal, for we have no intention of abandoning the mimesis as art theory not to be applied in the modern art any more, or to evaluate specific modern art works on the basis of the mimesis theory. The insane are regarded as the denial of the modern subject, but art as conception has supported the modern subject representatively and, ironically, now the modern irrational art contains these two incompatible concepts. So if we could find these correlates of insanity and art, we could renew both the cogito and mimesis in criticizing the traditional.