- A name applied to the system of philosophy based on the doctrine of evolution as enunciated by Herbert Spencer. See philosophy of evolution, under evolution.
- The philosophy of Spencer and Fiske, which asserts the existence of a real unknowable outside of the mind, the absolute relativity of all thought to ourselves, and that there is no knowledge except what is ultimately empirical science. It is specially opposed to the systems of Berkeley, Hume, Kant, Hamilton, and Comte.
- The doctrine that the material universe works automatically; affirmative atheism.
- The ethical doctrine which makes the welfare of mankind the highest good.