A word may be said in conclusion about the difference between the relation of Mr. Spencer on the one hand and Darwin on the other to the thought of the Nineteenth Century. The fact is not to be lost sight of that the principles of the Evolutionary, or, as Mr. Spencer prefers to term it, the Synthetic, philosophy were formulated before the publication of the “Origin of Species.” What the ultimately general acceptance of the theory propounded in Darwin’s work did for Mr. Spencer was precisely this: it greatly strengthened the biological evidence for the evolutionary hypothesis. That hypothesis was upheld, however, by evidence drawn not merely from biology, but from many other sources. Moreover, while the Darwinian theory of natural selection, supplemented as it was by the adoption of the Lamarkian factors,—the effect of use and disuse and the assumed transmissibility of acquired character,—merely attempted to explain the mode in which the changes in organic life have taken place upon the earth, the evolutionary hypothesis put forth by Mr. Spencer professed to be applicable to the whole sphere of the knowable. It is further to be borne in mind that Mr. Spencer has devoted a large part of his life to tracing in detail the applications of his fundamental principles to social, political, religious, and ethical phenomena. Darwin, on the other hand, strictly confined himself to the biological field, and left to disciples the task of indicating the bearing of the Darwinian theory upon sociology, theology, and morals.
The Complete Works of Herbert Spencer (The Synthetic Philosophy).
Also, “Facts and Comments,” by Herbert Spencer (Appleton’s).