II. SENSATIONS AND THOUGHTS.
#Professor Mach's problem.#
The difference between Professor Mach's view and mine may appear greater than it is, because the problem which Professor Mach treats in his article "The Analysis of the Sensations," lies in quite a different field from that of the problem of the relation of feeling to motion. The problem being different, the same and similar terms are not only used for different purposes, but demand also different comparisons. Professor Mach's symbols A B C … and α β γ … represent a contrast different from that of feeling and motion. They represent the contrast of sensations and thoughts. Sensations, such as green and hard, are colors, pressures, tastes, etc; thoughts are memory-images, concepts, volitions, etc.
Professor Mach says: "How the representative percepts of imagination and memory are connected with sensations, what relations they bear to them, as to this I dare venture no opinion…. Monism, as yet, I cannot thoroughly follow out; because I am lacking in clearness with regard to the relation of α β γ … to A B C …; but I believe that the first step towards a competent monism lies in the assertion that the same A B C … are both physical and psychical elements."
My symbols A B C … and α β γ … represent the contrast of physical and psychical elements, not of sensations and thoughts. Concerning thoughts, Professor Mach says he is much inclined to co-ordinate them with sensations so that his Greek symbols might differ from his Italic symbols not otherwise than the latter, viz. A B C …; differ among themselves. Taking this ground, I believe, it would be preferable to symbolise them accordingly among the Italic letters, perhaps as X Y Z. In the diagrams on page 407 they are called Μμ, Νν, Σς.
#Feeling, sense-impression and sensation defined.#
According to my terminology, feeling, as explained above, is the most general term expressing any kind and degree of subjective awareness. A sense-impression is a single irritation of one of the senses, the irritation being a special kind of motion plus a special and correspondent kind of feeling. A sensation is a sense-impression that has by repetition acquired meaning. A later sense-impression, when felt to be the same in kind as a former sense-impression, constitutes, be it ever so dimly, an awareness of having to deal with the same kind of cause of a sense-impression; thus giving meaning to it. By sensation, accordingly, I understand a sense-impression which has acquired meaning. And feelings that have acquired meaning, I should call mental states. Representative feelings (feelings that have a meaning) are the elements of mind.
#Thought and thinking defined.#
By thinking I understand the interaction that takes place between representative feelings. Such are the comparisons of sensations with memory-pictures, or of memory-pictures among themselves, the experimenting with memory-pictures so as to plan new combinations, etc. The products of thinking are called thoughts; and by thought in the narrower sense is commonly understood abstract thought which on earth is the exclusive privilege of man.
If I am not mistaken Professor Mach understands by sensations (represented by him as A B C …) what I should call sense-impressions; while thoughts, memories, and volitions (represented by him as α β γ …) form what I should call mind, or all kinds of mental states, that is, the domain of representations.
The higher spheres of thought, or representative feelings, grow out of and upon the lower spheres. Sense-impressions, as I have attempted to explain in the article "The Origin of Mind" (The Monist, No. 1), are the data which are worked out into concepts and ideas; they are the basis upon which the whole structure of mind rests. The reflex motions of simple irritations, being modified in higher spheres by the rich material of experience consisting of memory-images, and by the possibility of forethought created through experience, become volitions.
#Monism and the origin of mind.#
A monistic explanation of the rise of mind from elements that are not mind is possible only on the supposition that the objective processes of motion are not mere motions but that they are at the same time elements of feeling.
Is this not the same position as Professor Mach's, where he says that "the first step towards a competent monism lies in the assertion that the same A B C … are both physical and psychical elements"? and again: "The same A B C … are both elements of the world (the 'outer'[83] world namely) and elements of feeling."
[83] Professor Mach here says "outer world." I should prefer to replace it by the expression "objective world," because the motions of a man's brain belong to the outer world of all other men. To make sure of including the actions of my own body in this outer world, I should prefer the term "objective world," making feelings alone (to the exclusion of the subject's own motions) the constituents of the subjective world.
#Agreement with Professor Mach.#
Considering the two last-quoted sentences of Professor Mach, it appears to me that all differences vanish into verbal misunderstandings. Yet since I am not at all sure about it, I may be pardoned for becoming rather too explicit. The adjoined diagram may assist me in making my ideas clear.
[Illustration: Fig. I. Fig. II.]
#Explanation of the diagrams.#
Let the large circle of both figures represent a sentient being, a man. The periphery is his skin. The small circle enclosing K and L is a sensory organ; the other small circle enclosing M and N represents the hemispheres of his brain. A and B are processes taking place outside of the skin of this man. A produces an effect in K; B in L. The line R represents a reflex motion. M and N are concepts and abstract ideas derived from such impressions as K and L. The line S represents an act of volition.
All these symbols represent motions in the objective world. We know through physiological investigations that K, L, M, and N are motions; in our individual experience they appear as feelings.
The second figure represents in agreement with my system of symbols the states of awareness, in Greek letters. Certain physiological processes (K L R, M N S of Figure I) appear subjectively as states of awareness (i. e. κ λ ρ, μ ν ς of Figure II). Yet A and B remain to the thinking subject mere motions. If they possess also a subjective side, although only in the shape of potential feeling, it does not and it cannot appear.
#Sensations not elementary.#
Professor Mach calls green, hard, etc., which in a certain relation are our sensations, "the elements of the world." These processes characterised as "green," "hard," etc., are in my opinion too special and at the same time too complicated to be considered elementary. I grant that they are elements of mind, because if further analysed, they cease to be mental phenomena. But they are not elements per se, not elements of the world. It remains doubtful to me whether Professor Mach understands by his term "sensation" only K κ and L λ or the whole relations A K κ, and B L λ. Taking it that he represents A B C … as both elements of the world and sensations, it almost appears certain to me that his term "sensation" stands for the whole process A K κ, and that he considers the scientific analysis of this process into A the outside thing, into K the nerve-vibration corresponding in form to the outside thing, and κ the feeling that takes place in experiencing the sense-impression A K, as an artificial procedure that serves no other purpose than that of familiarising us with certain groups of elements and their connections. The processes A K κ, B L λ, in that case would be considered by Professor Mach as the actual facts, while the A and B, the K and L, the κ and λ represent mere abstract representations without real existence, invented by scientists in order to describe the realities A K κ, B L λ, etc., with the greatest exactness as well as economy of thought. In their separate abstractness they are the tools of science only and we must not take them for more than they are worth.
#Thoughts as mental implements.#
If this be so, I understand Professor Mach very well and I agree with him when he looks upon all M and N with their respective μ and ν as being "noumena, Gedankendinge, things of thought." They are mental tools. Sense-impressions are realities, but mental representations are implements; they are auxiliaries for dealing with realities; they are "the augers and saws" employed in the different fields of cognition.
#Persistence of the elements of mind.#
Professor Mach says in his article "The Analysis of the Sensations": "When I (the ego) cease to perceive the sensation green, when I die, then the elements no longer occur in their customary, common way of association. That is all. Only an ideal mental economical unity, not a real unity, has ceased to exist." The term sensations, it appears to me, can in this passage be interpreted neither as K κ only, nor as the whole relations A K κ, but as any A B C … relations; and since Professor Mach has not excluded from them the element of feeling, I should have to represent them by A α, B β, C γ…. Sensations as I understand the term (viz. A K κ, B L λ), are elements of mind; if they are further analysed they cease to be mental states. Says Professor Mach: "If I close my eye (K) withdraw my feeling hand (L), A B C … disappear. In this dependence A B C … are called sensations." Should we not rather say, they cease to be sensations, if this dependence ceases? Accordingly, sensations and sense-impressions are for this and for other reasons not indecomposable, not ultimate atoms. The elements of mind can be further analysed into the elements of the elements of mind. The elements of mind do not persist; but the ultimate elements of the elements of mind, whatever they are, do (or at least may) persist.
When speaking of the elements of the elements of mind we cease to deal with objects of actual experience as much as a physicist or chemist does who speaks about atoms. Nevertheless the analysis is as legitimate in our case as it is in the chemist's. If in the above quoted passage I am allowed to replace Professor Mach's term "sensations" by elements of sense-impressions, I should not hesitate unreservedly to accept his idea. These elements of sensations would be all kinds of natural processes, all kinds of motion. They would be physical actions which are not mere motions but also and at the same time elements of feeling.
#Ideas as contrivances for comprehension.#
It is true that abstract concepts, and especially scientific terms and theories, are mere contrivances to understand the connections among, and the qualities of, real things. Ideas are not the real things, but their representations, and some ideas are not even representations; they are solely of an auxiliary nature and comparable to tools. They are used as working hypotheses wherever the real state of things is in part hidden from us, until we have found the actual connections. As soon as the actual connections are found we can and must lay down our tools.
In a certain sense all words and concepts are tools for dealing with the realities they represent. But some words are tools in a special sense. They have been invented for acquiring a proper representation.
#The dignity of mental tools.#
Professor Mach says: "The implement is not of the same dignity or reality as A B C…." It appears to me that these implements (if they are of the right kind) have almost a higher dignity (although not reality) than the material to which they are applied. My respect for tools is very great, for tools are the most important factors, perhaps the decisive factors, in the evolution of man. The usage of tools has matured, nay created the human mind, and words,—scientific and abstract terms and theories not excluded,—are the most important and most sacred tools of all.
Some ideas, it is true, have to be laid aside like tools that are no longer wanted; but there are other ideas which we cannot lay aside, because they have more value than the ideas of a mere working hypothesis. Some ideas are indispensable and will remain indispensable; we shall always have to employ them in order to represent in our mind the connection between certain facts. If we see a train pass into a tunnel and emerge from it at the other end, we will connect in our mind these two sensations by the thought of the train's passage from one end to the other. This idea is not a sensation; it is a noumenon. Shall it therefore be called a mere noumenon, a tool that has to be discarded as soon as we are accustomed to expect a train to emerge from the one end of a tunnel soon after it has disappeared into it at the other end?
#Noumena legitimate, if representing realities.#
There are scientific concepts which, for some reason or other, can never become objects of direct observation; they can never become sensations. Nevertheless we must think them together with certain sensations as indispensable connecting events taking place behind the stage and hidden from our eyes. Our conception of a train hidden from sight in a tunnel, it is true, is a noumenon, but it is a legitimate noumenon, it represents a reality. So also many scientific ideas, although undoubtedly things of thought, are legitimate noumena. If they contain and in so far as they do contain nothing but formulated features of reality or inevitable conclusions from verified and verifiable experiences, these things of thought represent something real, which means that if we were in possession of microscopes of sufficient power, or if we could look behind the veil that hides them from our sight, we should see them, just as we should see the train if the rock through which the tunnel leads were transparent.