This project re-examined the concept of mental illness against the backdrop of the current changes in psychiatry in 4 research fields: (A) studying the changes in views regarding mental illness due to developments in biological psychiatry and cognitive therapy; (B) understanding the symptoms of mental illness from the perspectives of phenomenology, the theory of action, and cognitive philosophy; (C) conducting historical and theoretical investigation of diagnosis; and (D) understanding mental illness from the perspectives of the patients, their families, and any other support groups using community studies and disability studies. The results of the study were published in 15 papers and 59 oral presentations. Moreover, a 3-volume book series (in Japanese) called "Philosophy of Psychiatry" is in preparation (to be published in 2016).