The old dualistic notion of mind and matter, so prominent in Cartesianism, as two radically different kinds of substance, will hardly find defenders today. Rejecting this, we are driven to some form of hylopathy, otherwise called monism. Then the question arises whether physical laws on the one hand and the psychical law on the other are to be taken
(A) as independent, a doctrine often called monism, but which I would name neutralism; or,
(B) the psychical law as derived and special, the physical law alone as primordial, which is materialism; or,
(C) the physical law as derived and special, the psychical law alone as primordial, which is idealism.
The materialistic doctrine seems to me quite as repugnant to scientific logic as to common sense; since it requires us to suppose that a certain kind of mechanism will feel, which would be a hypothesis absolutely irreducible to reason, – an ultimate, inexplicable regularity; while the only possible justification of any theory is that it should make things clear and reasonable.
Neutralism is sufficiently condemned by the logical maxim known as Ockham’s razor, i.e., that not more independent elements are to be supposed than necessary. By placing the inward and outward aspects of substance on a par, it seems to render both primordial.
The one intelligible theory of the universe is that of objective idealism, that matter is effete mind, inveterate habits becoming physical laws.