1. i. e. in the sense of helping make psychology a systematized science. The practical significance of psychometrics is obvious.
2. W. James, Principles of Psychology, I. p. 546. Although many critics do not agree with James, this mere disagreement shows the presence of a problem. No one in his senses would say the proper outcome of thermometrics for instanceis just nothing. James was certainly in his senses.
3. E. L. Thorndike, The Measurement of Intelligence, New York, 1927-Thorndike's judgment although five years old could well be repeated today.
4. The writer is indebted to many sources for the ideas set forth in the following section. Rather than overburden the text with notes he wishes to admit this indebtedness here. The reader familiar with the writings of C. D. Broad, A. D. Ritchie, J. H. Woodger, L. v. Bertalanffy, H. Reichenbach, K. Lewin and W. Koehler will be more than faintly reminded of them in the following sections. The writer believes, however, that he is the first to apply the newer methodological ideas to an analysis of psychometrics and that he has some new ideas concerning the relationship between laws and instruments. Since completing this manuscript I have read Nagel, “Measurement”, Erkenntnis 2, 313–335, 1931. Although Nagel uses quite a different nomenclature and pursues the logical side of the question further than I shall do here, I find our general positions regarding laws, instruments and measurements very similar.
5. To a certain extent the writer agrees with this dictum. Measurement is necessary. This quarrel, however, as we shall see is concerning its relationship to law. It will be the writer's contention that this relationship has been completely misunderstood by the psychometricians.