830 THE AMERICAN JOURNAL OF SOCIOLOGY
must be longitudinal, genetic. Only thus can we arrive at a real understanding of the successive manifestation of the motive under investigation, and see the racial importance of the institu- tions in which it has from time to time embodied itself.
VI
In conclusion I may cite what I believe to be a good illustra- tion of my main position: it is found in the results of recent studies in criminology. In this case the study is not of solidarity but of its relative absence — of relative anti-sociality. Three great classes of criminals have been distinguished : the "born criminal;" the "occasional" or "emotional criminal;" and the "professional, habitual, deliberate criminal." The first of these is a criminal by heredity ; his acts are instinctive, impulsive, irre- sponsible. He should be treated as one having a chronic and perhaps incurable disease; and he should be placed where his tendencies will have no chance to manifest themselves.
The second, the "occasional" criminal, is the creature of sug- gestion, imitation, spontaneous emotion. It is the "occasion," the opportunity, that excites his passion and leads him to the criminal act. He should be given the aid of sound training and constant social support; for he is the "weak brother." For him the social environment is the important thing. His treatment is quite differ- ent from that given the criminal-born.
Finally, there is the third case, the professional, deliberate criminal. He is the real plotter against society, the real criminal, the "social" criminal, properly speaking; for his crime is reflective and voluntary. He adopts and devises means to accomplish his destructive ends. He knows himself and his resources, and can place himself and his fellows in the relation from which the profits of his crime are secured. He controls the social situation. The enemy of society, he should be pursued by all the agents of suppression that society has at its command.
Here, then, are our three types of solidarity negatively illus- trated. I find the illustration all the more instructive from its negative character. Bad heredity instead of good — the biological type; indulgence of vicious tendencies, of bad emotions, capricious
