happen to offset this idea. The child-placing agent sometimes assumes that a family home is the best place for every child, and the institution worker may lean too far the other way. The charity organization worker easily takes economic independence and family solidarity as being invariably the first considerations, while the health worker readily slights both. Each specialist, therefore, should ask himself to what particular overemphasis he is rendered liable by the nature of his task, and at that particular point he should be at especial pains to collect with impartiality the evidence on which he bases decisions.

3. Some Other Habits of Thought. There are, besides untested assumptions, other habits of thought that case workers of any kind are liable to fall into. We found that, until our case reading revealed the fact, some workers were unaware that they consulted the same favorite sources of information habitually, to the exclusion of other sources equally good or better, or that they cooperated heartily with only a certain few agencies-usually with those most accessible. Such methods mean a narrowed resourcefulness, with a few favorite remedies applied, a few combinations of stops pulled out, no matter what the demands of the situation or the resources available. Moreover, in changing from one city to another or from one field of social work to another, a worker must guard against holding fast to habits which may have been time-saving originally but which are useless under changed conditions.1 If a municipality's department of health or of correction has been unco-operative, one who faces a new administration or who leaves that community for another must be ready to drop the habit of doing without this help from public officials and must welcome a changed situation.

Again, the trend of modern social ideals often confirms in the more sophisticated case worker a habit of thinking in averages. Sometimes a case worker tends to become overabsorbed in the individual case, but a commoner failing of the modern type of

1 "When at shearings or markings they run the yearlings through a gate for counting, the rate of going accelerates until the sheep pass too rapidly for numbering. Then the shepherd thrusts his staff across the opening, forcing the next sheep to jump, and the next, and the next, until, Jump! says the flock-mind. Then he withdraws the staff, and the sheep go on jumping until the impulse dies as the dying peal of the bells." Austin, Mary: The Flock, p. 114. Boston, Houghton, Mifflin, and Co., 1906.

worker is that, oppressed by the condition of the mass, he misses a clear conception of the one client's needs. He thinks of him as one of a class. No client will meet with successful social treatment if so regarded, because it is usually his particular situation and not that part of his circumstances which he shares with others that is the immediate point at issue. Sidgwick has this general truth in mind when he says, "In forming a careful conclusion about a particular case, no one with any sense will use the method of probabilities if he has an opportunity of getting behind it and understanding the causes at work in the special case." Sidgwick means by his warning about the "method of probabilities" that, though a certain manifestation may have been proved statistically to have one significance in ninety-seven instances out of a hundred, and a quite different significance in the three others, this ratio, useful for action affecting a hundred in the mass, has a different sort of value in dealing with a single case about which more intimate knowledge is available. The value of such a ratio for the single case is that it necessarily gives rise to a hypothesis that the case in question is one of the ninety-seven. This hypothesis is useful in that it guides the inquiry which may or may not show the single case to be one of the majority. An assumption to this effect, however, where more knowledge is available about a particular case, the ratio does not justify. Were the case worker himself one of the three, would he care to be treated by a social practitioner whose habit it was to assume his client to be one of the ninetyseven? At the same time it would hardly be an intelligent practitioner who did not under these circumstances look upon it beforehand as probable that the client would turn out to be one of the ninety-seven.

There is always a risk that one's personal likes and dislikes may influence judgment. Take, for example, the prejudices and special tendencies that belong to the various racial and social groupings. Even those comparatively rare persons whose knowledge of the characteristics of many different social groupings of people is broad enough to have overcome mere class prejudice in themselves still belong to a certain habit-group and are attracted or repelled by like or unlike customs and manners in others. People of narrower 1 The Application of Logic, p. 69.

opportunity are almost without exception warped in their judgment by one class or racial prejudice or another, while at the same time they assume that social bias exists only in the other fellow. As such personal predispositions, when allowed swing, hinder his work, the social case worker needs to learn to set them aside.

Besides the risk in drawing inferences which arises from personal and professional predispositions, there is a risk that springs from the thinker's own desire in the particular instance, (1) to see his hypothesis confirmed, and (2) to secure prompt action. Such a hypothesis, for instance, as that about the Irishman with the prison record' becomes, because of its very ingenuity, the favorite child of our brain. In this case, it is true, the worker sought corroborating evidence. Nevertheless, the danger that commonly besets case workers is that of becoming so fond of some particular hypothesis that it will seem in no need of proof. This tendency may have especially serious consequences in the case of a first hypothesis that we have to make in a more or less obscure case in order to get started. The whole diagnosis may be vitiated by an unwarranted assumption at the beginning.

The worker's own desire to secure prompt action in a particular instance is also often responsible for invalid inference. In the case cited on p. 350, Chapter XVIII, in spite of contradictions in the evidence, the worker in his hurry to get an answer to the district attorney drew inferences in favor of the wife; whereas, had he stopped to test these inferences, he would have been led to get at once the additional facts that showed the husband to be the better of the two.

If we may count, as two essentials of the social diagnostician's equipment, his ability to weigh the risks involved in the types of evidence described in the chapter on Definitions, and his ability to measure and allow for the characteristics of human beings as witnesses a topic which has also received attention-there is still the third essential; namely, the ability to discriminate between fact and inference and, through inference, to deduce new facts. Then, when the items of evidence in a case seem to be at hand, there comes a time for considering them as a whole. The same reasoning and testing that has been applied to its separate items 1 See p. 86 of this chapter.

must be applied deliberately to the evidential mass. We shall return to this later in Chapter XVIII, in considering the comparison of part with part, as well as the final act of interpretation, the act of social diagnosis itself.

When we face each situation of our work with a mind alert to receive and follow suggestions, alert to utilize experience, and to make, try, and test one hypothesis after another; when we start out with entire willingness to prove or disprove our every inference, then the well tested inference reveals new fact, and new fact suggests new inference until gradually our case work acquires a strong, closely woven texture and our case histories become documents that will well repay study. It is upon such case history study, in fact, that social case work will have to depend, in large measure, for advancing standards and new discovery. Before turning to the practical details to which so large a part of the remaining chapters of this book will be devoted, it should be said with emphasis that there can be no good case work without clear thinking; that in social diagnosis sound reasoning is fundamental.

SUMMARY OF THIS CHAPTER

1. Inference is the reasoning process by which we pass from known fact to fact that is unknown. From many particular cases we may infer a general truth, or, as happens more often in case work, from a general truth we may infer some new fact about a particular case.

2. A first-stage or tentative inference is called a hypothesis. Resourcefulness in making and patience in testing hypotheses are fundamental to success in case work.

3. Corroboration of a tentative inference may have to be gathered deliberately or it may lie in our past experience. Past experience may also suggest a variety of hypotheses the richer the experience the greater the variety, and the greater also the likelihood of discovering the particular one which will prove to be correct.

4. Gaps in evidence may make it necessary to seek confirmation of a hypothesis through experiment, though the conditions of controlled experiment are achieved with difficulty in social work.

5. In addition to the risks involved in testimony which may be incompetent or biased, there are risks in the process of reasoning from testimony even when it is known to be reliable, including risks in the reasoner's own state of mind.

6. The risks involved in the reasoning process may occur in four ways: we may have a mistaken general rule, a mistaken particular case, a mistaken analogy, or a mistaken causal relation.

7. General rules that apply to human conduct are never of universal application. Often also the particular case assumed to come under a given general rule is different from what it is supposed to be, and therefore does not come under the rule in question.

8. Resemblances between two cases may exist, but at the points under consideration the resemblance may be only superficial. This is the danger in reasoning by analogy.

9. The common inclination is to seek for one cause. Where cause must be sought in human motives, however, we must expect to find that it is not a single simple cause but complex and multiple.

10. The chief risks arising from the case worker's own state of mind are found in his personal and professional predispositions and in his assumptions-in the salted-down rules, that is, which are the product of his experience.

11. The best safeguard against predispositions is to be aware of them. Once a personal prejudice, for example, is brought into the light of day, its influence upon thinking can be offset.

12. In the same way, if a worker knows his assumption to be what it is-unproven-he may venture to act upon it in the absence (after search) of evidence proving it to be unwarranted. Unwarranted case work assumptions persist because they are not examined and are taken on faith.

13. Other ways of thinking against which case workers may be warned are the habitual use of a few favorite sources of insight or co-operation, the continued disuse under changed circumstances of a source which was formerly not available, the habit of thinking in averages, and the habit of regarding with especial favor a first or an ingenious hypothesis.