When and why do we attribute a person's behavior to brain disease, and when and why do we not do so? Briefly, the answer is that we often attribute bad behavior to disease (to excuse the agent);never attribute good behavior to disease (lest we deprive the agent of credit); and typically attribute good behavior to free will and insist bad behavior called mental illness is a "no fault" act of nature.
Thomas Szasz, Cruel Compassion: Psychiatric Control of Society's Unwanted
behavior, mental-illness, responsibility