The report of the British Royal Commission, published in 1908, forms the starting point for many of the estimates made today. The commission added together the number of school children which were thought to require special classes with the number of defectives found in institutions, prisons and almshouses, or reported by its medical investigators. The total gave 0.46% of the general population as “mentally defective persons,” not including certified lunatics. From this amount should be deducted .06% who were insane but had not been certified as such, leaving 0.4% mentally deficient. This was not regarded by the Commission as an estimate, but was the number actually “enumerated by the medical investigators” in sixteen typical districts studied in England and Wales with a total population of 2,362,222 (83, VIII, p. 192). Turning to the school children we find that in the areas investigated there were 436,833 school children of whom 0.79% were found defective. Since this was an enumeration and not an estimate, the commission paid no attention to the discrepancy between 0.79% of the school children and 0.31% of the rest of the population. Tredgold, moreover, based his estimates of the frequency of the mental deficiency in England and Wales on the data of the Royal Commission without attempting to harmonize this discrepancy. This oversight has apparently been one source of the not uncommon difference between the estimates for school children and for the general population. One suspects that the fact that the elementary school population is about a fifth of the general population, has also mistakenly contributed to this error. The discrepancy of three to five times as large a frequency of deficiency among school children as in the general population certainly needs clearing up.
There is an escape from this dilemma which seems more reasonable than to attempt to account for the discrepancy by excessive mortality. When estimates are made concerning the school population the estimator is usually thinking of that group of feeble-minded which needs special school training and probably social assistance afterward. When estimates are made of the general population the estimator is likely to be thinking of that group which must be cared for permanently by society, mainly in institutions or colonies. For some time at least the state cannot be expected to undertake the indefinite care of all the deficients who should have, at once, simple industrial training, in special local schools or classes in order to survive, even with social assistance. This difference in the type of care contemplated seems most naturally to account for the discrepancy found with many writers, between their estimates for the school population and for the general population.
C. Desirable Versus Immediately Advisable Social Care
A second source of confusion arises when one investigator is thinking of the number of feeble-minded, the care of whom it is desirable that society should assume, and another is thinking of the feeble-minded, the care of whom it is advisable for society to assume at once. Considered in connection with a specific case the distinction is quite obvious. It is one thing to say that it would be desirable for the state to assume the indefinite care of a particular person, it is quite another thing to say that it would be advisable for the state to assume that care immediately, when one remembers the crowded condition of the institutions, the necessity of caring for the worst cases first, the possibility of the person being cared for by his own family or in a local school, the added public expense, the necessary neglect of other movements for social welfare if society assumes this expense, etc., etc.
When you magnify this problem in the mind of the estimator who is interested in the question of caring for the groups of feeble-minded, the result is that his estimates of the size of the groups are decidedly affected. For example, few would deny that the Site Commission of New York appointed to locate the colony for mental defectives, now known as the Letchworth Village, was emphasizing a program of permanent social care when it estimated the number of feeble-minded in New York. The Commission, “after taking into consideration the figures of the State and National census, and other data collected from institutions,” estimated that there were in New York state possibly 12,300 mentally defective persons (Editor's Note, 205, p. 84). This is less than 0.15% of the population and very low compared with most estimates.
The low estimates will generally be found to be influenced by considerations of public expense rather than the social unfitness of the lower group. Inasmuch as there are no sharp distinctions between different degrees of mental ability this consideration of public expense is perfectly proper. At the other extreme, however, are the eugenists who are convinced that it is desirable to isolate a large group at the lower range of ability. The member of the legislature will be concerned mainly with the question how much money will the public be willing to appropriate now for the care of these unfortunates. The eugenist will be thinking of an ideal rather far in the future towards which to work.
The diagnostician should take a conservative intermediate ground. He may leave to the court or other authorized tribunal to decide whether the public has the facilities available at present for caring for a particular weak-minded person, but he must decide whether expert scientific opinion at the present time will justify diagnosing this degree of deficiency as suitable for the special care provided for the feeble-minded. Whether it is advisable to care for the particular deficient at home, in a special local school, or in a state institution would be left to the legal authority to decide. Under present conditions, the diagnostician may possibly indicate whether the individual is deficient enough to justify social isolation, or merely to justify sending to a local elementary day school for deficients.
D. Percentages Suggested to Harmonize the Estimates
It is from the point of view of the diagnostician that we shall attempt to focus this question of the percentage of feeble-minded. We shall tentatively suggest limits as to the degrees of intellectual deficiency which we might be justified in regarding, under the present conditions of scientific knowledge as being low enough in intellectual capacity to justify particular forms of social care. Such estimates will be of value if they help to harmonize the conflicting opinions by bringing them into relation with the above analysis. We shall, therefore, compare the suggested percentages with a number of authoritative statements of the frequency of feeble-mindedness. By considering the differences in the nature of the estimations we may approach nearer to an understanding of the problem.
Since the percentages to be suggested are chosen from the point of view of diagnosis, they do not represent the number for which every community should immediately make financial provision. The expense is a local or a state question. It is so much affected by state conditions and by public policy that it probably must be determined in any state by a special commission. On the other hand, the laws already provide for caring for the feeble-minded in institutions or colonies and in special schools or classes, so that the estimates may help to guide diagnosticians who are called upon to decide whether a particular person might be rightfully regarded as deficient enough intellectually to justify committing him for permanent care to a state institution. In the present practise it is fairly clear that this distinction is made in the minds of different diagnosticians. It may ultimately be desirable that this differentiation between the types of social care be introduced into the law. Until then it will remain the duty of the court to determine what degree of social unfitness is intended by a particular law. The social concept of feeble-mindedness is just now undergoing a rapid evolution so that it would be impossible to predict how it may legally crystallize a generation hence.