Schizophrenia is well-known among mental illnesses for the severity of the thought disorders it involves, and for their widespread and spectacular manifestations: from deviant social behavior to delusion, not to mention affective and sensitive distortions. The goal of our interdisciplinary work is to (i) analyze linguistic troubles in conversational contexts in which one of the speakers is schizophrenic, (ii) construe how the concept of rationality and logicality may apply to them, and (iii) propose a formal representation about this specific manifestation.