The conception of a criminal diathesis does not stop merely with the notion that there is an inborn predisposition to crime. It considers further that offenses do not occur except under the stimulus of certain situations, even if such stimuli may be even more common than the tubercle-bacillus. The important question which it now puts to science is, “How much may the actual outbreak of delinquency be reduced with better methods of social prophylaxis?” Even if, “the chief tasks of social hygiene” are the “struggle against alcohol and against poor economic conditions,” as Aschaffenburg believes (68, p. 228), the chief emphasis from the best scientific work still seems to be that the problems of alcoholism, poverty and crime are more closely related to internal than to the external conditions which have thus far been measured. Guarding against the propagation of mental deficiency thus seems to be the most direct and hopeful method of attack, while the removal of infecting temptations, and training for greater resistance, should receive hearty, albeit subordinate emphasis.
[33]. See the next section for the significance of these coefficients of correlation.
CHAPTER XII. SUMMARY AND SUGGESTIONS
1. In our attempt to interpret the volume of results concerning tested delinquents, we have accepted the common conception that the feeble-minded are those who, through lack of mental development, are social deficients. They cannot survive in society without supervision. In the words of the English Mental Deficiency Act, “they require care, supervision, and control for their own protection or for the protection of others.” Our present scales of development tests do not detect those deficients whose failure is not directly due to intellectual incapacity. We have called those not detected by tests “purely conative cases,” to distinguish them from the tested deficients, who were said to be “intellectually deficient.” These conative cases would not be feeble-minded except for their incapacity for prolonged acts of will. Deficiency thus specialized in volition is so unusual, however, that the study of tested deficients gives us a useful picture of the problem of feeble-mindedness. To get a general view of the relation of deficiency to delinquency we determined conservative borderlines with the Binet scale and then reinterpreted on a common conservative basis the results obtained in more than a score of investigations covering thousands of objectively selected delinquents who had been tested. This has enabled us very largely to remove the question of the frequency of deficient delinquents from the realm of subjective opinion. We may now be certain that under present conditions the problem of deficiency is most pressing in institutions for female offenders. The evidence also points to the greater frequency of deficiency among prostitutes and repeaters, rather than among ordinary juvenile delinquents. We have thus been able to restate the problem of the deficient delinquent more conservatively and to modify some of the current conceptions. This enables us to direct our efforts more intelligently, with greater foresight, and more hope of success.
2. A still broader outcome of this interpretative study is to increase the precision of the test scales for use in the diagnosis of social deficiency. This has been accomplished by an extended reconsideration of the borderlines of deficiency on test scales, particularly the Binet scale. A percentage definition of tested deficiency is suggested for determining the borderline below which an individual may be presumed to be so deficient as to justify isolation, and for setting off a distance above this on the scale for which the test diagnosis of social deficiency should be regarded as uncertain. By this means it is hoped that the developmental scale may be made safer and more useful as an instrument for diagnosing feeble-mindedness.
A quantitative definition for tested deficiency has its main justification in its success in discovering social deficients and in predicting social failure. With this in mind the percentages suggested as representing the social deficients or uncertain cases in the community were chosen after a careful search through the evidence as to the success of children who had been in special classes or institutions and an extensive résumé and analysis of the best expert estimates of the frequency of social deficiency. The conclusion was that these percentages may tentatively be placed so that those who would at 15 years of age be in the lowest 0.5% in tested ability among a randomly selected group, may be presumed to be so deficient as to justify isolation. Above these the next 1.0% may be regarded as uncertain, since the bulk of them would require some supervision or guardianship during life. These two borderlines have then been located on the Binet scale for both the immature and the mature so far as possible from the available data. In particular these borderlines for the mature have been found for the first time on the basis of a randomly selected group. Besides the records of Minneapolis delinquents these Binet borderlines for a typical random population of 643 15-year-olds is the main contribution of new data in the study.
The practical consideration of these borderlines in Part One and their location on the test scale emphasizes that a test diagnosis is only symptomatic, that the suggested borderlines on the Binet scale are determined from limited data which may not be verified in other communities, that the scale itself is imperfect, and that the results should be checked by other tests, especially by the school retardation, a new example of which is given for the Minneapolis delinquents. The plan of the percentage method of describing the borderlines readily allows for adjustment to more complete data or better developmental scales. The alternative to the use of a test record as symptomatic of deficiency is dependence upon the history of the case or physical signs, such as are found among Mongolians, cretins, epileptics, etc. These signs have been found among only about 13% of the deficient children ([141]). Expert opinion given on the history of the case is clearly less reliable than such opinion checked by even a crude objective test standard. In Part Two of this study the theoretical background for the percentage definition is compared with that of other quantitative definitions on the basis of the conceptions of mental measurement and mental development.
3. In attempting to suggest methods for diagnosis and control, which our summary of the scientific data makes necessary, we shall be led beyond the evidence presented in this study. To those to whom these suggestions may seem remoted from the foregoing pages, it may be said that they are the result not only of a review of the available research work, but also an outcome of several years observation of the practical handling of this problem both in this country and abroad. In that study I was led to visit several scores of institutions and schools for delinquent or deficient children in Austria, England, France, Germany, Italy and Switzerland. The methods suggested below for the case of the deficient delinquent are only modifications of what has been observed in actual operation.
An adequate diagnosis of deficiency involves not only the accurate knowledge of the present mental condition of the individual, but an understanding of the causes of that condition. This requires a complete family and social history of the individual and a knowledge of the medically removable handicaps. It would seem, therefore, that such a diagnosis may be best made by a commission which shall include a physician as well as a psychologist, or else by an expert in mental development who is provided with adequate facilities and assistance for discovering other handicaps than innate incapacity. For the group of uncertain and conative cases a final diagnosis should, if possible, be made only after prolonged observation in a temporary home school.