In planning Psychologies of 1930 we have tried to profit from all the serious criticisms that came to Psychologies of 1925. Associationism, Act Psychology, and Functionalism have been included in their historical setting, but the reader should not presume that these three schools are discussed by partisans in the same way as are the other schools. Professors Brett and Carr have acted largely as historians only in bringing these three schools to the convenient attention of students of this book, though Professor Carr himself is certainly in the direct line of descent from Functionalism.
The former category of "Purposive Psychology" is here presented under the rubric "Hormic Psychology" and is expounded by the leading exponent of both rubrics.
The large group of students who have come from Titchener's laboratory are represented by four different points of view. It may be made self‐ evident whether or not it is appropriate to apply the term "Structuralism" to the doctrines of this group.
The present-day theories of the Leipzig laboratory are added to the Berlin group under the more general title of "Configurational Psychologies," it being definitely understood that this classification is applied by the Editor only.
The three leading Russian schools of psychology are here presented in comparable, theoretical form for the first time in the English language.
The Factor School of Psychology and three Analytical Psychologies appear also as distinct additions to the program of Psychologies of 1925. A separate section on some non-sectarian fundamental problems has also been added.
As I can recall the various types of helpful criticisms and comments concerning Psychologies of 1925 that have come my way during the past five years, I do not believe I have failed to observe a single one. If I have failed to heed any of them, it has been entirely my fault and I hope the suggestions will be repeated.
Now that psychology is rapidly coming of age, it is no longer a symbol of maturity for a psychologist to neglect the theoretical foundations of his science. Those who have suggested that it is futile to examine theoretically the hypotheses on which all experimental work is based have not been obeyed during the preparation of this volume, but are being quietly left to the tender mercies of time.
I acknowledge with gratitude the assistance of Dr. Luberta M. Harden, who has supervised the preparation of the manuscripts for the printer and has made the indices.
March 25, 1930 . . .