The independence and underivability of the psychical, the incomparability

of its uniformities with those of mechanical or physico-chemical laws, has

proved itself so clear and incontrovertible, notwithstanding all the

distortions of naturalism, that it is now regarded as a self-evident fact,

not only among philosophers and epistemologists, and technical

psychologists, but for the last decade even among all thinking men, and
r /> "materialism" is now an obsolete position. It was too crude and too

contrary to all experience to define the relation between physical and

mental, as if the latter were a mere secretion of the former, although a

very subtle one, or a mere epi-phenomenon of it, in such a way that all

reality and effectiveness was on the side of the physical.

In place of this, another theory has become widespread, which claims to

define the relation of the two series of phenomena better and more

adequately: the theory of psychophysical parallelism. It is not new. There

are occasional indications of it even in Aristotle's psychology. It was

suggested by Descartes in his automaton theory, by the occasionalists in

their parable of the two watches running in exact agreement; it was

developed by Spinoza and Leibnitz, and refined by the idealistic

philosophers, by Schopenhauer, Fechner, and the modern psychologists. The

form in which it is most prevalent now is that given to it by Spinoza, and

he is usually referred to in connection with it. Its general tenor is as

follows: The physical cannot be referred back to the psychical, nor the

psychical to the physical. Both orders of phenomena run side by side as

parallels that never separate. Both represent a concatenation of causes

complete in itself, that is never broken, or interrupted, or completed.

And in both there is real causality. Thought really causes thoughts and

feelings. Movement really causes movements. But the one series is always

strictly correlated with the other, and corresponds with it. And thus all

existence is double, and man is an obvious illustration of this. To every

thought, feeling, or exercise of will there corresponds some excitement,

movement or change in the body. I will: my arm moves. Subtle nervous

processes run their course in my brain, and I think. That I will has its

sufficient reasons, its causes lie entirely in the preceding state of my

mind, in motives of feeling, in ideas which again have their efficient

causes in a previous psychical condition, and so on. And that my arm moves

has its efficient cause in the stored-up energies of the muscle-substance,

in the stimulus and impulse conveyed by the motor nerve from the brain.

And these conditions have their purely physiological causes and reasons

again in preceding purely physiological states and processes. (It goes

without saying that a mechanical theory of life is the necessary

presupposition of this parallelistic theory.) But both sets of processes

correspond exactly one to another, and the first is only the inner aspect

of the second, and the second the outer aspect of the first. Thus it is

quite true that my arm moves when I will. But in reality it is quite as

true to say that when my arm moves I will. But we must not substitute

"because" for "when." This theory must maintain, and does maintain, that

even the most abstract and subtle ideas, the deepest processes of

consciousness, have some corresponding bodily processes, either in the

brain or in the nervous substance generally, and, on the other hand, that

no physical process is without this psychical inwardness. The result is

that this inwardness and soul are attributed also to the purely material

world, the world of "dead" matter. In this way it is believed that

everything gets its due; the thorough mechanical explicability of bodily

phenomena, and the law of the conservation of energy and of matter, and,

on the other hand, very decisively also, the independence and uniqueness

of law which can no longer be denied to the psychical. And from this

latter standpoint sharp protests are raised against all materialistic

distortions. The only thing denied is the old idea of the "influxus

physicus," the idea, that is, that mind can operate beyond itself and take

effect on the physical world, and conversely the physical world upon it.

This again is regarded as a breach of the law of the conservation of

energy. For if the bodily affects consciousness, then at a given moment a

certain amount of energy must be transformed into something that is not

energy. And if consciousness affects the bodily, a process of movement

must suddenly occur, for which no previous equivalent of energy can be


This standpoint is most impressively set forth in Paulsen's widely read

"Introduction to Philosophy." The same ideas form the central feature in

the work of Fechner, which is having such a marked renaissance to-day.

It seems as though all higher estimates of spirit, even the religious

estimate, could quite well rest upon this basis. For full scope is here

given to the idea that mind and the mental sciences have their own

particular field. God, as the absolute all-consciousness and

self-consciousness, comprehending within Himself all individual

consciousness, is thought of as the eternal correlate of this universe in

space. And the theory has room also for a belief in immortality. Of all

imaginative attempts to make the idea of immortality clear and possible,

undoubtedly that of Fechner is the grandest and most effective. And it,

too, is based entirely upon the idea of parallelism. (Yet as a matter of

fact it could be shown that neither mortality nor immortality really fit

into the scheme of this conception.)

Though its main features are very similar as set forth by its various

champions, this theory differs according to the way in which this

astonishing and mysterious co-ordination, this parallelism itself, is

explained. How is it that "thought" and "extension" can correspond to one


The answer may be either naively dogmatic, that this is one of the great

riddles of the universe, and that we must simply take it for granted.

Others declare with Spinoza that the two series of phenomena are only the

two sides of one and the same fundamental being and happening, which may

be designated as natura sive deus, and that what is inwardly unified

expresses itself outwardly in these two forms of being. But because both

sides, thought and extension, are only expressions of one and the same

fundamental substance, they correspond exactly to one another. The best

illustration of this is Fechner's simile of the curved line. It is concave

on one side, convex on the other, and thus entirely different on the two

sides. But at every point the concavity corresponds exactly to the

convexity. And this is possible because the two are the inner and the

outer aspects of the same line.

Others, again, go back to the fundamental ideas of critical idealism, and

declare the whole extended world accessible to the senses and the

mechanical-physical nexus of cause and phenomena, to be simply the form of

appearance in which the fundamentally spiritual existence presents itself

to our senses. Body, movement, physiological processes, are all nothing

more than the will, to speak with Fichte and Schopenhauer, or the idea, or

the spirit itself, which appears thus to sensory beings. Other theories,

some of them new, are also put forward.