to settle whether the end in itself is desirable.  Often the end may be a matter of course for every reasonable being.  The extreme case is presented by the applied science of medicine, where the physician subordinates all his technique to the end of curing the patient.  Yet if we are consistent we must acknowledge that all his medical knowledge can prescribe to him only that he proceed in a certain way if the long life of the patient is acknowledged as a desirable end.  The application of anatomy, physiology, and pathology may just as well be used for the opposite end of killing a man.  Whether it is wise to work toward long life, or whether it is better to kill people, is again a problem which lies outside the sphere of the applied sciences.  Ethics or social philosophy or religion have to solve these preliminary’ questions.  The physician as such has only to deal with the means which lead toward that goal.

We must make the same discrimination in the psychotechnical field.  The psychologist may point out the methods by which an involuntary confession can be secured from a defendant, but whether it is justifiable to extort involuntary confessions is a problem which does not concern the psychologist.  The lawyers or the legislators must decide as to the right or wrong, the legality or illegality, of forcing a man to show his bidden ideas.  If such an end is desirable, the psychotechnical student can determine the right means, and that is the limit of his office.  We ought to keep in mind that the same holds true for the application of psychology in economic life.  Economic psychotechnics may serve certain ends of commerce and industry, but whether these ends are the best ones is not a care with which the psychologist has to be burdened.  For instance, the end may be the selection of the most efficient laborers for particular industries.  The psychologist may develop methods in his laboratory by which this purpose can be fulfilled.  But if some mills prefer another goal,—­for instance, to have not the most efficient but the cheapest possible laborers,—­entirely different means for the selection are necessary.  The psychologist is, therefore, not entangled in the economic discussions of the day; it is not his concern to decide whether the policy of the trusts or the policy of the trade-unions or any other policy for the selection of laborers is the ideal one.  He is confined to the statement; if you wish this end, then you must proceed in this way; but it is left to you to express your preference among the ends.  Applied psychology can, therefore, speak the language of an exact science in its own field, independent of economic opinions and debatable partisan interests.  This is necessary limitation, but in this limitation lies the strength of the new science.  The psychologist may show how a special commodity can be advertised; but whether from a social point of view it is desirable to reinforce the sale of these goods is no problem for psychotechnics.  If a sociologist insists that