ACTUALITY THEORY is the view that the real is not a thing or a state at rest, but an activity or a process.
In philosophy the theory is as old as Heraclitus who conceived ultimate reality as an incessant becoming, not as static being. In modern philosophy Spinozism may be regarded as a form of this theory. For, notwithstanding the important place which the con ception of "substance" holds in the philosophy of Spinoza, Spinoz ism when correctly interpreted is essentially dynamic, not static, in character. Of subsequent philosophers the following (among others) may be regarded as upholders of the actuality theory in some form or other. Fichte conceived of the real as the infinite activity of the absolute ego. Hegel regarded it as an absolute process, a kind of dialectical evolution. Schopenhauer described it as volitional activity or striving. Wundt likewise thought of reality as a complex of volitional activities or processes. For Bergson "there are no things, only activities" (Creative Evolu tion). Of philosophical men of science Mach, Ostwald, and White head (among others) may be claimed as supporters of the actuality theory. Indeed the whole drift of present day science is to regard "events" rather than "things" as the ultimate components of the world of reality.
In psychology the actuality theory is mainly concerned with the nature of the soul or mind. According to the popular view, which is also supported by many psychologists, the mind or soul is a substance, an abiding something which owns the mental ex periences of knowing, feeling, and willing, or which exercises these activities. As against this "substantial" view of the soul, the actuality theory in psychology treats the soul as just the complex or system of these activities, experiences, or processes, and no more. The view appears to be as old as Protagoras and Aristotle. It is quite explicit in Spinoza, for whom the human soul is just a complex of ideas, and ideas are not dead, static pictures on a canvas, but living activities. Hume likewise stated that his in trospective attempt to catch a glimpse of his soul revealed to him nothing but "a bundle" of sensations, etc. Of modern psy chologists, Fechner, Hoffding, James, Baldwin, Ebbinghaus, Sully, and Wundt (among others) may be classed among the supporters of the actuality theory, while other psychologists are more or less in sympathy with it, though they regard the whole question as pertaining to philosophy rather than to psychology. On one point, however, all modern psychologists are agreed, namely, that mental experiences are essentially events, activities, or processes, not states. And this agreement is largely the result of the contention of the upholders of the activity theory.