The difficulties in accounting for the psychological mechanisms of psychosis are similar to those just presented in relation to the neurochemistry of schizophrenia. Actually, since the mechanism of normal belief formation remains unknown, it might appear premature, even presumptuous, to propose a mechanism for abnormal beliefs. Dr. Kapur adhered to a viewpoint common in modern cognitive psychology that supposes that psychotic beliefs reflect a quantitative change from normal belief mechanisms. Such an approach has led to the specific cognitive therapy of psychosis. But as with dopamine antagonism, cognitive therapy is not as effective as it should be if this view of psychosis is correct. The alternative is that psychosis involves a qualitatively distinct belief mechanism. While this does not immediately suggest novel therapeutic approaches, it has been previously suggested to account for the symptoms of schizophrenia (1).