Page:Popular Science Monthly Volume 39.djvu/399

Here follows a brief account of the doctrine of interaction as it appeared in the writings of Descartes, who, it is said, gave clear and distinct form to the current doctrine which helped greatly to lay bare its weak points. "To Descartes, therefore, belongs the credit of having set the problem of the relation of mind and body. For to the current notion in its vaguer form there is no difficulty in this relation. With legitimate heedlessness, the practical usage of speech ignores theoretical difficulties. Ordinary language no more regards the fact that physiology and psychology are opposed to the notion of brain and consciousness acting on one another than it respects the doubt of Copernicus as to the sun really moving round the earth. Moreover, the practical usage of speech has been formed under the influence of a partly spiritualistic, partly materialistic metaphysics."

Materialism.—The case is made clearer when one of these two factors is, without more ado, struck out.

And since the perception of the external material world takes the leading part in our ordinary ideas, while our inner self-consciousness is with difficulty educated to a like clearness and distinctness, it is perhaps the most natural thing to identify materiality with reality, and to conceive of the mental as an effect of the material. Modern materialism usually treats the mental as a function of the material. It has found a solid basis in the doctrine of the persistence of matter and energy and in that of physiological continuity. As a method of natural science it is unanswerable. But it is another affair when the method is converted into a system. It has a perfect right to treat all changes and functions of the organism, and in particular of the brain, as material; but it goes further when it maintains that the phenomena of consciousness are only changes and functions of the brain, and in this consists its encroachment.

Prof. Höffding alludes to the position of Carl Vogt, who in his time gave great offense by declaring that "as contraction is the function of muscles, and as the kidneys secrete urine, so, and in the same way, does the brain generate thoughts, movements, and feelings." In Vogt's comparison, "doubtless the chief emphasis is to be laid on the secreting activity and not on the product. The principle, however, remains the same. Among cautious physiologists with some philosophical training, the doctrine that conscious activity is a function of the brain may be sometimes met with." But the strict physiological use of the term function must contradict such a doctrine. To say that contraction is the function of the muscle, only means that it is a certain form and a certain condition of the muscle in movement. It is just as material when functioning as when at rest. The conception function (in the physiological sense) implies, just as much as the conception matter or product, something presented as an object of intuition in the form of space. But thought and feeling can not be pictured as objects in space, or as movements; we get