West German terrorists exhibit the characteristics of madness according to official definitions: 1) subjects' absolute certainty that they are right, 2) subjects' imperviousness to lessons of experience or to logical arguments, 3) absurdity of subjects' views in the context of West German society, and 4) therapists' lack of empathy with the reasons underlying their actions on a basic level. However, terrorists still cannot be diagnosed as schizophrenic, even though their psychological processes are reminiscent of that condition. Their obsessive ideas totter on the borderline between sickness and health, and follow a pattern similar to Hitler's ideas, with hate directed against an imaginary enemy whom they seek to destroy. The term monoperceptosis is used by the author for socially negative obsessive ideas which espouse contrary values, are based on false perceptions, and are destructive to persons and property. Characteristics of monoperceptosis are infantile feelings of omnipotence, loss of a sense of reality, extreme aggressiveness, a chronic identity crisis, narcissism and egocentricity, loss of internal value systems, rejection of psychiatric intervention, inability to form meaningful male-female relationships, and facility for repressing reality. The case study of a 25-year-old laborer who murdered his adoptive parents serves as an example of monoperceptosis combined with social infantilism, a condition which is described in detail. A parallel is drawn between the young laborer and terrorists. However, the infantilism of the terrorists is attributed to regression rather than to retarded development. A diagnosis of monoperceptosis combined with infantilism could be considered grounds for partial mental incompetence. Notes are supplied. --in German.