Psychophysical parallelism: are mind and body parallel aspects rather than interacting substances?

Wilhelm Wundt, answered from the texts and cited to the page.

The position in brief

Do not ask whether the mind acts on the body or the body on the mind, for the question mistakes what mind and body are. There are not two substances here that might push each other about. There is one reality of experience, and it may be regarded in two ways: from within, as the immediate inner experience that is the psychical; from without, as the physiological process that is the physical.¹²

These two series run parallel and coordinated — every psychical process has its physiological concomitant — but neither causes the other, because they are not two things but two aspects of one. This is psychophysical parallelism, and it frees psychology at a stroke from two errors: the materialism that would reduce the mind to the brain, and the spiritualism that would make it a soul-substance lodged in the body.³

And it rests on a deeper principle: the actuality of mind. The mental is not a thing at all, not a soul, not a substance that has states; it is an activity, a process, actual only in its occurring. Psychology studies this actual inner experience and finds in it its own causal laws — creative synthesis, the growth of psychical energy, the heterogony of ends — which are not borrowed from physics and not reducible to it.⁴ Mind is autonomous: a domain of activity with laws of its own.⁵

Sources

1. We may speak in such instances, perhaps, of the influence of mind upon body, or vice versa. But we always mean, if we do not say, that the word ' influence' is not to be taken sensu stricto: that, for instance, a direct causal influence cannot be exerted by psychical term upon physical, but only upon the psychical process which this physical represents by parallelism.

   Lectures on Human and Animal Psychology, pp. 461–463

2. In this sense outer and inner experience are identical with mediate and immediate, or with objective and subjective forms of experience. All these terms serve to designate, not different spheres of experience, but different supplementary points of view in the analysis of an experience which is presented to us as an absolute unity. 7.

   Outlines of Psychology, pp. 392–393

3. In this case matter is thought of as made up of similar atoms of a lower order (monistic, or monadological spiritualism), or the mind atom is regarded as specifically different from matter proper (dualistic spiritualism, see table p. 17). In both its materiaUstic and spiritualistic forms, the concept mind substance does nothing for the interpretation of psychological experience.

   Outlines of Psychology, p. 391

4. The question' of the extent of the validity of this principle of psychophysical parallelism can be approached either from the physical or mental side. From the former point of view, our direct experience of the parallelism tells us in plain terms enough that its range is exceedingly limited.

   Lectures on Human and Animal Psychology, pp. 455–456

5. Necessary as these distinctions are, then, we must still never forget that they are based upon abstractions, — that they do not carry with them any real separation of objects. Objectively, we can regard the individual mental processes only as inseparable elements of interconnected wholes.

   Principles of Physiological Psychology Vol I, p. 20

Where the argument is made

• Principles of Physiological Psychology (1904, the doctrine of psychophysical parallelism and the principle of the actuality of mind)
• Outlines of Psychology (1907, the account of the mental as activity rather than substance and the autonomy of psychical causality)

How the argument was received

Wundt's solution to the mind-body problem and the metaphysical frame of his whole psychology, holding a middle position against both materialism and dualist interactionism. Parallelism was widely held in the psychology of his day (Fechner, and in a different key the identity theorists) and was attacked from both flanks: the interactionists (McDougall's animism) charged that it makes the evident efficacy of mind an illusion and leaves the exact coordination of the two series an unexplained miracle; the materialists charged that a parallel mental series doing no causal work is an idle wheel, and moved toward identity or epiphenomenalism. Wundt's distinctive contribution, the "actuality" principle — mind as process rather than substance — has drawn renewed interest from functionalist and process-oriented philosophies of mind that reject the soul-substance without reducing the mental to the physical.