ABSTRACT
Most definitions of abnormality include deviance, distress, dysfunction, and dangerousness. While many instances of self-starvation are clearly a sign of abnormality, death through hunger strike in the service of a cause might be considered a heroic act. It is impossible to provide a generally applicable definition of abnormal behavior. However, most now agree that there are many instances of behavior and mental process that it is useful to consider 'abnormal', and which psychiatrists, clinical psychologists, and others can attempt to help. From around 500 BC, Greek and Roman philosophers and physicians viewed a number of mental disorders as being diseases caused by physical dysfunction. In the second half of the 19th century, the somatogenic medical model became dominant. As conceptions of psychological abnormality change, so classification systems have to be changed. The medical model implies that there are a number of distinct mental illnesses..
