The influence of biological science in general upon psychology has been very great. Every important development in science contributes to the popular consciousness, and indeed to philosophy, some new conception which serves for a time as a most valuable category of classification and explanation. To biology is due the conception of organism. Traces of the notion are found long before the great rise of biological science, and, in particular, Kant has given a complete and careful exposition of it; but the great rôle which the "organic" conception has played of late is doubtless due in largest measure to the growth of biology. In psychology this conception has led to the recognition of mental life as an organic unitary process developing according to the laws of all life, and not a theatre for the exhibition of independent autonomous faculties, or a rendezvous in which isolated, atomic sensations and ideas may gather, hold external converse, and then forever part. Along with this recognition of the solidarity of mental life has come that of the relation in which it stands to other lives organized in society. The idea of environment is a necessity to the idea of organism, and with the conception of environment comes the impossibility of considering psychical life as an individual, isolated thing developing in a vacuum.
This idea of the organic relation of the individual to that organized social life into which he is born, from which he draws his mental and spiritual sustenance, and in which he must perform his proper function or become a mental and moral wreck, forms the transition to the other great influence which I find to have been at work in developing the New Psychology. I refer to the growth of those vast and as yet undefined topics of inquiry which may be vaguely designated as the social and historical sciences,-- the sciences of the origin and development of the various spheres of man's activity. With the development of these sciences has come the general feeling that the scope of psychology has been cabined and cramped till it has lost all real vitality, and there is now the recognition of the fact that all these sciences possess their psychological sides, present psychological material, and demand treatment and explanation at the hands of psychology. Thus the material for the latter, as well as its scope, have been indefinitely extended. Take the matter of language. What a wealth of material and of problems it offers. How did it originate; was it contemporaneous with that of thought, or did it succeed it; how have they acted and reacted upon each other; what psychological laws have been at the basis of the development and differentiation of languages, of the development of their structure and syntax, of the meaning of words, of all the rhetorical devices of language. Any one at all acquainted with modern discussions of language will recognize at a glance that the psychological presentation and discussion of such problems is almost enough of itself to revolutionize the old method of treating psychology. In the languages themselves, moreover, we have a mine of resources, which, as a record of the development of intelligence, can be compared only to the importance of the paleontological record to the student of animal and vegetable life.
But this is only one aspect, and not comparatively a large one, of the whole field. Folk-lore and primitive culture, ethnology and anthropology, all render their contributions of matter, and press upon us the necessity of explanation. The origin and development of myth, with all which it includes, the relation to the nationality, to language, to ethical ideas, to social customs, to government and the state, is itself a psychological field wider than any known to the previous century. Closely connected with this is the growth of ethical ideas, their relations to the consciousness and activities of the nation in which they originate, to practical morality, and to art. Thus I could go through the various spheres of human activity, and point out how thoroughly they are permeated with psychological questions and material. But it suffices to say that history in its broadest aspect is itself a psychological problem, offering the richest resources of matter.
Closely connected with this, and also influential in the development of the New Psychology, is that movement which may be described as the commonest thoughts of everyday life in all its forms, whether normal or abnormal. The cradle and the asylum are becoming the laboratory of the psychologist of the latter half of the nineteenth century. The study of children's minds, the discovery of their actual thoughts and feelings from babyhood up, the order and nature of the development of their mental life and the laws governing it, promises to be a mine of greatest value. When it was recognized that insanities are neither supernatural interruptions nor utterly inexplicable "visitations," it gradually became evident that they were but exaggerations of certain of the normal workings of the mind, or lack of proper harmony and co-ordination among these workings; and thus another department of inquiries, of psychical experiments performed by nature, was opened to us, which has already yielded valuable results. Even the prison and the penitentiary have made their contributions.
If there be any need of generalizing the foregoing, we may say that the development of the New Psychology has been due to the growth, on the one hand, of the science of physiology, giving us the method of experiment, and, on the other, of the sciences of humanity in general, giving us the method of objective observation, both of which indefinitely supplement and correct the old method of subjective introspection.
So much for the occasioning causes and method of the New Psychology. Are its results asked for? It will be gathered, from what has already been said, that its results cannot be put down in black and white like those of a mathematical theory. It is a movement, no system. But as a movement it has certain general features.
The chief characteristic distinguishing it from the old psychology is undoubtedly the rejection of a formal logic as its model and test. The old psychologists almost without exception held to a nominalistic logic. This of itself were a matter of no great importance, were it not for the inevitable tendency and attempt to make living concrete facts of experience square with the supposed norms of an abstract, lifeless thought, and to interpret them in accordance with its formal conceptions. This tendency has nowhere been stronger than in those who proclaimed that "experience" was the sole source of all knowledge. They emasculated experience till their logical conceptions could deal with it; they sheared it down till it would fit their logical boxes; they pruned it till it presented a trimmed tameness which would shock none of their laws; they preyed upon its vitality till it would go into the coffin of their abstractions. And neither so-called "school" was free from this tendency. The two legacies of fundamental principles which Hume left, were: that every distinct idea is a separate existence, and that every idea must be definitely determined in quantity and quality. By the first he destroyed all relation but accident; by the second he denied all universality. But these principles are framed after purely logical models; they are rather the abstract logical principles of difference and identity, of A is A and A is not B, put in the guise of a psychological expression. And the logic of concrete experience, of growth and development, repudiates such abstractions. The logic of life transcends the logic of nominalistic thought. The reaction against Hume fell back on certain ultimate, indecomposable, necessary first truths immediately known through some mysterious simple faculty of the mind. Here again the logical model manifests itself. Such intuitions are not psychological; they are conceptions bodily imported from the logical sphere. Their origin, tests, and character are all logical. But the New Psychology would not have necessary truths about principles; it would have the touch of reality in the life of the soul. It rejects the formalistic intuitionalism