For a long time it seemed as if the theory of parallelism was to gain general acceptance. One might write a whole history of the gradually increasing criticisms of, and reactions from the academic theories which had become almost canonical. But we may here confine ourselves to the most general of the objections to the parallelistic theory. They apply to the general [pg 343] idea of parallelism itself, and affect the different standpoints of the parallelists in different degrees. The theory in no way corresponds to what we find in ourselves from direct experience. It is only with the greatest difficulty that we can convince ourselves that our arm moves only when and not because we will. The consciousness of being, through the will, the actual cause of our own bodily movements is so energetic and direct and certain, that it maintains its sway in spite of all objections, and confuses the argument even of the parallelists themselves. Usually after they have laid the foundations of a purely parallelistic theory, they abandon it again as quickly as possible, and revert to the expressions and images of ordinary thought. Indeed we have no clearer and more certain example of causality in general than in our own capacity for controlling changes in our own bodies. Further, a very fatal addition and burdensome accessory of the parallelistic theory is involved in the two corollaries it has above and beneath it. On the one hand there is the necessity for attributing soul to everything. These mythologies of atom-souls, molecule-souls, this hatred and love which are the inner aspects even of the simple facts of attraction and repulsion among the elements, fit better into the nature-philosophy of Empedocles and Anaxagoras than into ours. The main support, indeed the sole support, of this position is that this world of the infinitely little cannot be brought under control as far as its “soul” is concerned. Thus we can [pg 344] impute “a soul” to it without danger. On the other hand, there is a difficulty which made itself felt even in regard to Spinoza's system. All bodily processes must have psychical processes corresponding to them, said Spinoza. Conversely, all ideas in their turn must have bodily processes. To the system including all bodily processes corresponds the sum-total of psychical processes. This sum-total we call the soul. And in its entirety it is the idea corporis. If “soul” were really nothing more than this, the theory of parallelism might be right. But it is more than this. It rises above itself, and becomes also the idea ideÆ; it is self-consciousness and the consciousness of the ego; it makes its own thought and the laws of it, its feelings and their intensity—its experiences in short—a subject of thought. How does this fit in with parallelism? Wundt himself, the most notable modern champion of parallelism, admits and defines these limits of the parallelistic theory on both sides.

Furthermore, the theory of parallelism, notwithstanding its opposition to materialism, must presuppose that localisation of psychical processes of which we have already spoken, and to which all naturalism appeals with so much emphasis. Because of the fact that particular psychical functions seem to be limited to a particular and definable area of the brain-cortex, or to a spot which could be isolated on a particular convolution, it seemed as if naturalism could prove that “soul” was obviously a function of this particular [pg 345] organ or part of an organ. According to the theory of parallelism this does not follow. It would assert: “What in one aspect appears to be a psychical process, appears in another aspect to be a definite physiological process of the brain.” Yet it is clear that in order to gain support for the doctrine of mutual correspondence, parallelism has also the same interest in such localisation. For this is the only method by which it can empirically control its theory. But this whole idea of localisation does not hold good to anything like the extent to which the members of the naturalistic school are wont to assert that it does. In regard to this point, too, there has been considerable disillusioning in recent years. Perhaps all that can be said is, that localisation of psychical processes is a fact analogous to the fact that sight is associated with the optic nerves and hearing with the auditory nerves. Progressive investigation leads more and more clearly to the recognition of a fact which makes localisation comparatively unimportant, namely, the vicarious functioning of different parts of the brain. In many cases where this or that “centre” is injured, and rendered incapable of function, or even extirpated, the corresponding part of the mind is by no means destroyed along with it. At first the mind may suffer from “the effect of shock” as the phrase runs, but gradually it may recover and the same function may be transferred to another part of the brain, and there be fulfilled sometimes less perfectly, sometimes [pg 346] quite as perfectly as before. We had to deal with this fact of vicarious function in discussing the general theory of life. It is one of the greatest difficulties in the way of the mechanistic and materialistic theories. But it must give some trouble to the parallelists too.

We need not speak of the wonderful duplication of all existence which parallelism must establish, though it is difficult to evade the question how a natura sive deus could have come, so superfluously, to say the same thing twice over. Superfluously, for since both are alike self-contained and independent of one another, one can have no need of the other.

One objection, however, may be urged against both parallelism and materialism, which makes them both impossible, and that is, automatism. Both parallelism and materialism maintain that the sequence of physical processes is complete in itself and can be explained in terms of itself. All physical processes! Not only the movements of the stars, the changes in inanimate matter, the origin and evolution of the forms of life, but also what we call actions, for instance the movements of our arms and our legs, and the complicated processes affecting the breathing organs and tongue, which we call “speech.” Every plant, every animal, every human being must be as it is and where it is, must move and act, must perform its functions, which we explain as due to love or hate, to fear or hope, even if there were no such thing as sensation, will, idea, neither love nor hate, fear nor hope. More than this, all that [pg 347] we call history, building towns and destroying them, carrying on war and concluding peace, uniting into states and holding national assemblies, going to school and exercising mouth and tongue, argument, making books and forming letters, writing Iliads, Bibles, and treatises on the soul or on free will, holding psychological congresses and talking about parallelism;—all this must have been done even if there had been no consciousness, no psychical activity in any brain! This is the necessary consequence to which the theories of parallelism and materialism lead. If it does not follow, then there was from the outset no meaning in establishing them. But the monstrosity of their corollary is fatal to them. It is idle to set up theories in which it is impossible to believe.

There is another consideration that affects parallelism alone. Since the theory credits each of the two series with a closed and sufficient causal sequence, each of which excludes the other, it does away with causality altogether. That the one line runs parallel with the other excludes the idea that a unique system of laws prevails, determining the character and course of each line. One of the two lines must certainly be dependent, and one must lead. Otherwise there can be no distinctness of laws in either. Let us recall our illustration of the cloud shadows once more; the changing forms of the shadows correspond point for point with those of the clouds only because they are entirely dependent upon them. We may illustrate it in this way: a parallel may be drawn to [pg 348] an ellipse, it also forms a closed curved line. But it is by no means again an ellipse, but is an entirely dependent figure without any formula or law of its own. Parallelism must make one of its lines the leading one, which is guided and directed by an actual causal connection within itself. The other line may then run parallel with this, but its course must certainly be determined by the other. And as the line of corporeal processes, with its inviolable nexus of sequences, is not easily broken, parallelism, after many hard words against materialism, frequently returns to that again or becomes inconsistent. But if one says that the two aspects of phenomena are only the forms of one fundamental phenomenon, that means taking away actual causality from both alike, and leaving only a temporal sequence. For then the actually real is the hidden something that throws the cloud-shadows to right and left. But in the sequence of shadows there is no causal connection, only a series of states succeeding one another in time, and this points to a causal connection elsewhere.

It is easy enough to find examples to prove that the mental in us influences the bodily. But the most convincing, deepest and most trustworthy of these are not the voluntary actions which are expressed in bodily movements, nor even the passions and emotions, the joy which makes our blood circulate more quickly, and the shame which brings a flush to our foreheads, the suggestions which work through the mind towards the reviving, vitalising or healing of the body, but the cold and [pg 349] simple course of logical thought itself. Through logical thinking we have the power to correct the course of our conceptions, to inhibit, modify, or logically direct the natural course, as it would have been had it been brought about by our preceding physiological and psychical states, if they were dominant and uncontrolled. But if so, then we must also have the power, especially if it be widely true that physiological states correspond to psychical states, to influence, inhibit, modify the nerve-processes in our brain, or to liberate entirely new ones, namely, those that correspond to the corrected conceptions.

The law of the conservation of energy is here applied in as distorted a sense as we detected before in regard to the general theory of life. And what we said there holds good here also. That something which is in itself not energetic should determine processes and directions of energy is undoubtedly an absolute riddle. But to recognise this is less difficult than to accept the impossibilities which mechanism and automatism offer us here, even more pronouncedly than in regard to the theory of life. Perhaps one of the familiar antinomies of Kant shows us the way, not, indeed, to find the solution of the riddle, but to recognise, so to speak, its geometrical position and associations. We have already seen that inquiry into the causal conditions of processes lands us in contradictions of thought, which show us that we can never really penetrate into the actual state of the matter.