[CHAPTER VI]
THE NATURE OF THE SOUL
Fundamental Importance of Psychology—Its Definition and Methods—Divergence of Views Thereon—Dualistic and Monistic Psychology—Relation to the Law of Substance—Confusion of Ideas—Psychological Metamorphoses: Kant, Virchow, Du Bois-Reymond—Methods of Research of Psychic Science—Introspective Method (Self-Observation)—Exact Method (Psycho-Physics)—Comparative Method (Animal Psychology)—Psychological Change of Principles: Wundt—Folk-Psychology and Ethnography: Bastian—Ontogenetic Psychology: Preyer—Phylogenetic Psychology: Darwin, Romanes
The phenomena which are comprised under the title of the “life of the soul,” or the psychic activity, are, on the one hand, the most important and interesting, on the other the most intricate and problematical, of all the phenomena we are acquainted with. As the knowledge of nature, the object of the present philosophic study, is itself a part of the life of the soul, and as anthropology, and even cosmology, presuppose a correct knowledge of the “psyche,” we may regard psychology, the scientific study of the soul, both as the foundation and the postulate of all other sciences. From another point of view it is itself a part of philosophy, or physiology, or anthropology.
The great difficulty of establishing it on a naturalistic basis arises from the fact that psychology, in turn, presupposes a correct acquaintance with the human organism, especially the brain, the chief organ of psychic activity. The great majority of “psychologists” have little or no acquaintance with these anatomical foundations of the soul, and thus it happens that in no other science do we find such contradictions and untenable notions as to its proper meaning and its essential object as are current in psychology. This confusion has become more and more palpable during the last thirty years, in proportion as the immense progress of anatomy and physiology has increased our knowledge of the structure and the functions of the chief psychic organ.
What we call the soul is, in my opinion, a natural phenomenon; I therefore consider psychology to be a branch of natural science—a section of physiology. Consequently, I must emphatically assert from the commencement that we have no different methods of research for that science than for any of the others; we have in the first place observation and experiment, in the second place the theory of evolution, and in the third place metaphysical speculation, which seek to penetrate as far as possible into the cryptic nature of the phenomena by inductive and deductive reasoning. However, with a view to a thorough appreciation of the question, we must first of all put clearly before the reader the antithesis of the dualistic and the monistic theories.
The prevailing conception of the psychic activity, which we contest, considers soul and body to be two distinct entities. These two entities can exist independently of each other; there is no intrinsic necessity for their union. The organized body is a mortal, material nature, chemically composed of living protoplasm and its compounds (plasma-products). The soul, on the other hand, is an immortal, immaterial being, a spiritual agent, whose mysterious activity is entirely incomprehensible to us. This trivial conception is, as such, spiritualistic, and its contradictory is, in a certain sense, materialistic. It is, at the same time, supernatural and transcendental, since it affirms the existence of forces which can exist and operate without a material basis; it rests on the assumption that outside of and beyond nature there is a “spiritual,” immaterial world, of which we have no experience, and of which we can learn nothing by natural means.
This hypothetical “spirit world,” which is supposed to be entirely independent of the material universe, and on the assumption of which the whole artificial structure of the dualistic system is based, is purely a product of poetic imagination; the same must be said of the parallel belief in the “immortality of the soul,” the scientific impossibility of which we must prove more fully later on ([chap. xi].). If the beliefs which prevail in these credulous circles had a sound foundation, the phenomena they relate to could not be subject to the “law of substance”; moreover, this single exception to the highest law of the cosmos must have appeared very late in the history of the organic world, since it only concerns the “soul” of man and of the higher animals. The dogma of “free will,” another essential element of the dualistic psychology, is similarly irreconcilable with the universal law of substance.
Our own naturalistic conception of the psychic activity sees in it a group of vital phenomena, which are dependent on a definite material substratum, like all other phenomena. We shall give to this material basis of all psychic activity, without which it is inconceivable, the provisional name of “psychoplasm”; and for this good reason—that chemical analysis proves it to be a body of the group we call protoplasmic bodies the albuminoid carbon-combinations which are at the root of all vital processes. In the higher animals, which have a nervous system and sense-organs, “neuroplasm,” the nerve-material, has been differentiated out of psychoplasm. Our conception is, in this sense, materialistic. It is at the same time empirical and naturalistic, for our scientific experience has never yet taught us the existence of forces that can dispense with a material substratum, or of a spiritual world over and above the realm of nature.
Like all other natural phenomena, the psychic processes are subject to the supreme, all-ruling law of substance; not even in this province is there a single exception to this highest cosmological law (compare [chap. xii].). The phenomena of the lowly psychic life of the unicellular protist and the plant, and of the lowest animal forms—their irritability, their reflex movements, their sensitiveness and instinct of self-preservation—are directly determined by physiological action in the protoplasm of their cells—that is, by physical and chemical changes which are partly due to heredity and partly to adaptation. And we must say just the same of the higher psychic activity of the higher animals and man, of the formation of ideas and concepts, of the marvellous phenomena of reason and consciousness; for the latter have been phylogenetically evolved from the former, and it is merely a higher degree of integration or centralization, of association or combination of functions which were formerly isolated, that has elevated them in this manner.