But Herbart would not only base his psychology on metaphysics and experience, but likewise upon mathematics. He discovered the possibility of this in the fact of inhibition. Mathematical psychology aims to discover definite laws governing the reciprocal inhibition of ideas. Psychical energies cannot be measured by movements in space like those of physics; but Herbart thought it possible to start from the fact that, inasmuch as all ideas strive to preserve themselves, the sum of inhibition in any given moment must be the least possible. The problem therefore consists in determining how to divide the inhibition among the various coincident or aspiring ideas.— This presupposition rests upon Herbart's metaphysical theories, according to which every idea is a self-preservative act of the psychical Real. Herbart failed to attain clear results and such as could be harmonized with experience on the basis of this presupposition by the method of calculation, and his significance as a psychologist does not rest upon this attempt to reduce psychology to an exact science.
Herbart excludes ethics—here he is an out-and-out Kantian—completely from theoretical philosophy. He is of the opinion that there is no scientific principle which can at once be subsumed as the explanation of reality and the guarantee of value.—Our value judgments are spontaneously and often unconsciously determined by certain practical ideas. Such ideas are patterns which hover before the mind whenever we judge of the harmonic or disharmonic relation between the conviction and the actions of a man or between the strivings of a number of men in relation to one another. Whenever we discover disharmony between a man's conviction and the trend of his actual desires, it conflicts with the idea of inner