Finally, to the two foregoing attributes of the human soul (substantiality and simplicity), we must add a third and crowning attribute, namely, spirituality. It is this, and this alone, that differentiates the human from the bestial soul, which latter is but an incomplete complement of matter, incapable of existence apart from matter, and doomed to perish with the dissolution of the organism, as the cylindrical form of a candle perishes with the consumption of the wax by the flame.
All the psychic activities of the brute, such as sensation, object-perception, imagination, associative memory, sensual emotion, etc., are organic functions of the sensitivo-nervous type. In all of them the agent and recipient is not the soul alone, but the psycho-organic composite of soul and organism, that is, the soul-informed sensory and central neurons of the cerebrospinal system. The sensory neurons are nerve cells that transmit centerward the excitations of physical stimuli received by the external sense organs or receptors, in which their axon-fibers terminate. These receptors and sensory neurons are extended material organs proportioned and specialized for receiving physical impressions from external bodies, either directly through surface-contact with the bodies themselves or their derivative particles (e.g. in touch, taste and smell), or indirectly through surface-contact with an extended vibrant medium such as air, water, or ether (e.g. in hearing and sight). The central neurons of the cerebral cortex are, as it were, the tablets, upon which the excitations transmitted thither by the sensory neurons, record the extended neurograms that constitute the physical basis of the concrete imagery of memory and imagination. Interior senses, then, like memory and imagination, merely continue and combine what was preëxistent in the exterior senses. Their composite imagery is rigidly proportioned to the extended neurograms imprinted on the cerebral neurons, and these neurograms, in turn, are determined both qualitatively and quantitatively by the physical impressions received by the receptors, and these impressions, finally, are exactly proportioned to the action of the material stimuli in contact with the receptors. Thus the composite images of imagination as well as those of direct perception are proportioned to the underlying neurograms of the cortex and correspond exactly, as regards quality, intensity, and extensity, to the original stimulus affecting the external receptors. Hence men born blind can never imagine color, nor can men born deaf ever imagine sound. An inextended principle, such as the discarnate soul, cannot receive or record impressions from extended vibrant media, or from extended corporeal masses. For this the soul requires the intrinsic coöperation of material receptors. Now, the highest cognitive and appetitive functions of the brute (e.g. sense-perception and emotion) are, as has been stated, of the sensitivo-nervous or psycho-organic type, that is, they are functions in which the material organism intimately coöperates; brute animals give no indication of having so much as a single function, which proceeds from the soul alone and which is not communicated to the organism. Hence the bestial soul is “totally immersed” in matter; as regards both operation and existence, it is “intrinsically dependent” upon its material complement, the organism. It never operates save in conjunction with the latter, and its sole reason for existence is adequately summed up in saying that it exists, not for its own sake, but merely to vivify and sensitize the organism. Consequently, the brute soul, though inextended and incorporeal, belongs, not to the spiritual, but to the material, order of things.
Is the human soul equally material in nature, or does it belong to the spiritual category of being? The state of the question has long since been formulated for us by Aristotle: “A further difficulty,” he says, “arises as to whether all attributes of the soul are also shared by that which has the soul or whether any of them are peculiar to the soul itself: a problem which it is imperative, and yet by no means easy, to solve. It would appear that in most cases it neither acts nor is acted upon apart from the body: as, e.g., in anger, courage, desire, and sensation in general. Thought, if anything, would seem to be peculiar to the soul. Yet if thought is a sort of imagination, or something not independent of imagination, it will follow that not even thought is independent of the body. If, then, there be any functions or affections of the soul that are peculiar to it, it will be possible for the soul to be separated from the body: if, on the other hand, there is nothing peculiar to it, the soul will not be capable of separate existence.” (“Peri Psyches,” Bk. I, chap. I, 9.) We shall see that the human soul has certain operations which it discharges independently of the intrinsic coägency of the organism, e.g., abstract thought (not to be confounded with the concrete imagery of the imagination) and deliberate volition (to be distinguished from the urge of the sensual appetite). Hence, over and above the organic functions, which it discharges in conjunction with the material organism, the human soul has superorganic functions, of which it is itself, in its own right, the exclusive agent and recipient. In other words, it exists for its own sake and not merely to perfect the body.
The Aristotelian argument for the spirituality of the human soul consists in the application of a self-evident principle or axiom to certain facts of internal experience. The axiom in question is the following: “The nature of an agent is revealed by its action”; or, to phrase it somewhat differently: “Every being operates after the same manner that it exists.” The factual data, to which reference is made, are man’s higher psychic functions, in which the soul alone is the active cause and receptive subject, namely: the rational or superorganic functions of thinking and willing. The argument may be formulated thus: Every agent exists after the same manner that it operates. But in rational cognition and volition the soul acts without the co-agency of the material organism. Therefore the human soul can exist without the coexistence of the material organism. But this is tantamount to saying that it is a spiritual reality irreducible to matter and incapable of derivation from matter. For we define that as spiritual, which exists, or is, at least, capable of existing, without matter. Consequently, the human soul is a supermaterial and immortal principle, which does not need the body to maintain itself in existence, and can, on that account, survive the death and dissolution of its material complement, the organism. Such a reality, as we have seen, cannot be a product of evolution, but can only come into existence by way of creation.
The axiom, that activity is the expression or manifestation of the entity which underlies it, needs but little elucidation. In the genesis of human knowledge, the dynamic is prior to both the static and the entitive. We deduce the nature of the cause from the changes or effects that it produces. Action, in short, is the primary datum upon which our knowledge of being rests. It is the spectrum of solar light emitted by them, which enables us to determine the nature of the chemical elements present in the distant Sun. It is the reaction of an unknown compound with a test reagent that furnishes the chemist with a clue to its composition and structure. It is the special type of tissue degeneration caused by the specific toxin engendered by an invisible disease germ that enables the pathologists to identify the latter, etc., etc. So much for the axiom. Regarding the psychological facts, a more lengthy exposition is required. To begin with, there is prima facie evidence against the contention that the higher psychic functions in man are independent of the organism. Injury and degeneration of the cerebral cortex result (very often, at least) in insanity and idiocy. Reason, therefore, is in some way dependent upon the organism. Babies, too, are incapable of rational thought until such a time as the nervous system is fully developed. Obviously, then, rational functions cannot be spiritual, inasmuch as they are not independent of the organism.
This time-honored objection of materialists is based on a misapprehension. It falsely assumes that spirituality excludes every kind of dependence upon a material organism, and that our assertion of the soul’s independence of matter is an unqualified assertion. This, however, is far from being the case. It is only intrinsic (subjective), and not extrinsic (objective), independence of the organism which is here affirmed. An analogy from the sense of sight will serve to make clear the meaning of this distinction. In the act of seeing a tree, for example, our sight is dependent upon a twofold corporeal element, namely, the eye and the tree. It is dependent upon the eye as upon a corporeal element intrinsic to the visual sense, the eye being a constituent part of the agent and subject of vision; for it is not the soul alone which sees, but rather the soul-informed retina and neurons of the psycho-organic composite. The eye enters as an essential ingredient into the intimate constitution of the visual sense. It is a constituent part of the specific cause of vision, and it can therefore be said with perfect propriety that the eye sees. Such dependence upon a material element is called intrinsic or subjective dependence, and is utterly incompatible with spirituality on the part of that which is thus dependent. But the dependence of sight upon an external corporeal factor, like a tree or any other visible object, is of quite a different nature. Here the corporeal element is outside of the seeing subject and does not enter as an ingredient into the composition of the principal and specific agent of vision. True the tree, which is seen, is coïnstrumental as a provoking stimulus and an objective exemplar, but its concurrence is of an extrinsic nature, not to be confounded with the intrinsic co-agency of the eye in the act of vision. Hence, in no sense whatever can the tree be said to see; for the tree is merely an object, not the principal and specific cause, of vision. When the dependence of an agent upon a corporeal element is of this sort, it is termed extrinsic or objective dependence. Such dependence upon a material element is perfectly compatible with spirituality, which does, indeed, exclude all materiality from the specific agent and subject of a psychic act, but does not necessarily exclude materiality from the object contemplated in such an act. Hence the fact that the thinking soul must abstract its rational concepts from the concrete imagery of a cerebral sense, like the imagination, in no wise detracts from its spirituality, because the dependence of abstract thought upon such imagery is objective or extrinsic, and not subjective or intrinsic.
Psychologists of the sensationalist school have striven to obscure the fundamental distinction which exists between rational thought and the concomitant cerebral imagery. It is, however, far too manifest to escape attention, as the healthy reaction of the modern school of Würzburg indicates. “It cost me great resolution,” says Dr. F. E. Schultze, a member of this school, “to say, that, on the basis of immediate experiment, appearances and sensible apprehensions are not the only things that can be experienced. But finally I had to resign myself to my fate.” (“Beitrag zur Psychologie des Zeitbewusstseins,” p. 277.)
But thought is not only distinct from imagery, often there is marked contrast between the two, both as regards subjective, and objective, characters. Thus our thought may be perfectly clear, precise, and pertinent, while the accompanying imagery is obscure, fragmentary, and irrelevant. “What enters into consciousness so fragmentarily, so sporadically, so very accidentally as our mental images,” exclaims Karl Bühler (also of Würzburg), “can not be looked upon as the well-knitted, continuous content of our thinking.” (Archiv. für die ges. Psychol., 9, 1907, p. 317.) The same contrast exists with respect to their objective characters. Imagination represents by means of one and the same image what reason represents by means of two distinct concepts, e.g. an oasis and a mirage; and, vice versa, reason represents under the single general concept of a rose objects that imagination is forced to represent by means of two distinct images, e.g., a yellow, and a white rose. Imagery depicts only the superficial or exterior properties of an object, whereas thought penetrates beneath the phenomenal surface to interior properties and supersensible relationships. The sensory percept apprehends the existence of a fact, while the rational concept analyzes its nature. Hence sense-perception is concerned with the reality of existence, while thought is concerned with the reality of essence.
Certain American psychologists employ the term imageless thought to designate abstract concepts. The expression is liable to be misunderstood. It should not be construed as excluding all concomitance and concurrence of sensible imagery, in relation to the process of thought. What is really meant is that sensible appearances do not make up the sum-total of our internal experiences, but that we are also aware of mental acts and states which are not reducible to imagery. In other words, we experience thought; and thought and imagery, though concomitant, are not commensurable. The clarity and coherence of thought does not depend on the clarity or germaneness of the accompanying imagery, nor is it ever adequately translatable into terms of that imagery. Thus the universal triangle of geometry, which is not right, nor oblique, nor isosceles, neither scalene nor equilateral, neither large nor small, neither here nor there, neither now nor then, is not visualizable in terms of concrete imagery, although we are clearly conscious of its significance in geometrical demonstrations. Imagery differs according to the person, one man being a visualist, another an audist, another a tactualist, another a motor-verbalist, etc. But thought is the same in all, and consequently it is thought, and not imagery, which we convey by means of speech. Helen Keller, whose imagery is mainly motor and tactile, can exchange views with an audist or visualist on the subject of geometry, even though the amount of imagery which she has in common with such persons is negligible. “Eine Bedeutung,” says Bühler, “kann man überhaupt nicht vorstellen, sondern nur wissen,” and Binet, in the last sentence of his “L’Étude expérimentale de l’intelligence,” formulates the following conclusion: “Finally—and this is the main fact, fruitful in consequences for the philosophers—the entire logic of thought escapes our imagery.”
Nevertheless, thought does not originate in the total absence of imagery, but requires a minimal substrate of sensible images, upon which it is objectively, if not subjectively, dependent. The nature of this objective dependence is explained by the Scholastic theory concerning the origin of concepts. According to this theory, the genesis of our general and abstract knowledge is as follows: (1) We begin with sense-perception, say of boats differing in shape, size, color, material, location, etc. (2) Imagination and sense-memory retain the composite and concrete imagery synthesized or integrated from the impressions of the separate external senses and representing the boats in all their factual particularity, individuality, and materiality, as existent here and now, or there and then, as constructed of such and such material (e.g., of wood, or steel, or iron, or concrete), as having determinate sizes, shapes, and tonnages, as painted white, or gray, or green, as propelled by oar, or sail, or turbine, etc. (3) Then the active intellect exerts its abstractive influence upon this concrete imagery, accentuating the essential features which are common to all, and suppressing the individuating features which are peculiar to this or that boat, so that the essence of a boat may appear to the cognitive intellect without its concomitant individuation—the essence of a boat being, in this way, isolated from the peculiarities thereof and its various qualities from their subject (representatively, of course, and not physically). (4) The imagery thus predisposed, being no longer immersed in matter, but dematerialized by the dispositive action of the active intellect, becomes coïnstrumental with the latter in producing a determination in the cognitive intellect. (5) Upon receiving this determination, the cognitive intellect, which has hitherto been, as it were, a blank tablet with nothing written upon it, reacts to express the essence or nature of a boat by means of a spiritual representation or concept—the abstractive act of the active intellect is dispositive, inasmuch as it presents what is common to all the boats perceived without their differentiating peculiarities; the abstractive act of the cognitive intellect, however, is cognitive, inasmuch as it considers the essence of a boat without considering its individuation. Such is the abstractive process by which our general and abstract concepts are formed. From a comparison of two concepts of this sort the process of judgment arises, and from the comparison of two concepts with a third arises the process of mediate inference or reasoning. Volition, too, is consequent upon conception, and hence an act of the will (our rational appetite), such as the desire of sailing in a boat, entails the preëxistence of some conceptual knowledge of the nature of a boat. Volition, therefore, presupposes thought, and thought presupposes imagination, which supplies the sensible imagery that undergoes the aforesaid process of analysis or abstraction. Such imagery, however, is a function of the cerebral cortex, and, for this reason, the normal exercise of the imagination presupposes the cerebral cortex in a normal physiological condition; and anything that disturbs this normal condition of the cortex will directly disturb the imagery of the imagination, and therefore indirectly impede the normal exercise of conceptual thought, which is abstracted from such imagery. Hence it is clear that the activity of both the intellect and the will is objectively dependent upon the organic activity of the imagination, and, in consequence, indirectly dependent upon the physiological condition of the cerebral cortex, which is the organ of the imagination. Since, however, this dependence is objective rather than subjective, it does not, as we have seen, conflict with the spirituality of rational thought.