and the posterior cannot be reversed, so that the conclusion, for example, should prove the premises; and this is the true source of the belief in irreversibility. Thus, by this test of reversibility, the relativity of the mechanical standpoint, and, with it, that of psychology, is brought out.
The writer defends the claims of positivism as against both subjective idealism and materialism. In a recent work by E. Boirac, L'idée du phénomène, a view is maintained, which is in substance that of Berkeley, that since all we know is phenomena, and since phenomena exist in and rest upon consciousness, there can be no reality but consciousness. Such doctrine rests upon verbal equivocation. We can believe in phenomena as facts having mutual relations to one another, even when not present to our consciousness. Moreover, consciousness alone and in itself cannot be real,—as such it must be absolute immobility, changelessness, and therefore unconsciousness. The phenomenon is not adequately thought as a mere subjective appearance, but rather as a change pertaining to a dynamic order which constitutes that conception of unity which thought demands. The dynamic continuity of facts, mental and material alike, is thus the legitimate unity which is offered by positivism in contradistinction to the idealism which spiritualizes matter, or the materialism which materializes spirit. Thought does not create nature, but^n reflecting it completes it, and in completing interprets it. The idea is in us, not in the things; but the things are the necessary conditions of our ideas.
There are two physical laws which, at first sight, seem inconsistent with the theory of evolution. These are the principle of the conservation of energy, and the principle of Carnot, which states that, in a material system left to itself, the energy is continually being used, and so that the tendency is toward a state of equilibrium. Viewed singly, these physical laws seem opposed to each other; but when taken together they are easily reconciled. The quantity of the total energy remains constant, but its quality continually grows poorer. Energy is always being changed into some form that is less utilizable. The same laws hold in the organic as in the inorganic world, but with this difference. A living being is able to make use of more of the energy at its disposal; and as it rises higher in the scale, the amount of wasted energy becomes less. Therefore there is no conflict between evolution and the physical laws in question. As evolution proceeds, although the amount of utilizable energy diminishes, the amount of energy used increases.
