We are now, I think, in a position not only to understand the independence of Spencer's and Darwin's work in relation to each other, but the significance of this independence. Because Spencer's thought descended from the social and political philosophy of the eighteenth century (which in turn was a rendering of a still more technical philosophy), and employed the conceptions thus derived to assimilate and organize the generalized conceptions of geology and biology, it needed no particular aid from the specialized order of scientific methods and considerations which control the work of Darwin. But it was a tremendous piece of luck for both the Darwinian and Spencerian theories that they happened so nearly to coincide in the time of their promulgation. Each
in very much the same way in which Darwin borrowed the Malthusian
doctrine of population. The social idea first found biological form for itself, and then was projected into cosmological terms. I have no doubt that this represents the general course of Spencer's ideas. In the essay on "Progress," Spencer specifically refers to the law of the evolution of the individual organism as established "by the Germans—the investigations of Wolff, Goethe, and von Baer." The law referred to here is that
development consists in advance from homogeneity to heterogeneity. He there transfers it from the life history of the individual organism to the record of all life; while, in the same essay, he expressly states that, if the nebular hypothesis could be established, then we should have a single formula for the universe as a whole, inorganic as well as organic. And upon page 36 he speaks of that "which determines progress of every kind—astronomic, geologic, organic, ethnological, social, economic,
artistic."
One need only turn to some of the methodological writings of Spencer to see how conscious he was of the method which I have attributed to him. The little essay entitled "An Element in Method," and certain portions of his essay entitled, "Professor Tait on the Formula of Evolution," are particularly significant. The latter indicates the necessity of making a synthesis of deductive reasoning, as exhibited in mathematical physics, with the inductive empiricism characteristic of the biological
sciences; and charges both physicist and zoölogist with one-sidedness. The former essay indicates that, in forming any generalization which is to be used for deductive purposes, we ought to take independent groups of phenomena which appear unallied, and which certainly are very remote from each other. I am inclined to think that Spencer's method of taking groups of facts, apparently wholly unlike each other, such as those of the formation of solar systems, on one side, and facts of present social life, on the other, with a view to discovering what he calls "some common trait," has, indeed, more value for philosophic method than is generally recognised. In a way, he has himself justified the method, since his Synthetic Philosophy is, speaking from the side of method, precisely this sort of thing, astronomy and sociology forming the extremes, and biology the mean term. But, of course, Spencer's erection of the "common trait" into a force, or law, or cause, which can immediately be used deductively to explain other things, is quite another matter from this heuristic or
methodological value. But this note has already spun itself out too long.
