It will require some generations yet to find out even approximately what rôle the wonderful process of struggle and selection plays in species-making. But it is becoming clear in part wherein and why Darwin and, following him, all the rest of us, have gone so wide of the mark concerning it. The subject is too vast to touch more than summarily here.
It is the very essence of the human mind to inquire after the causes of whatever happens in this world of ours. It is the essence of science to hold that these causes are natural, not supernatural. Darwin became convinced that species arise naturally while yet the philosophy of living things in which he had been nurtured contained practically nothing concerning any natural cause that could be assigned to species production. Special or supernatural causation was held as a dogma rather in default of evidence of natural causes than from proof of supernatural ones. So religious superstition and dogmatism had a free field here. Darwin's naturalist instincts said: "Since species arise naturally, natural causes sufficient therefor must exist. If they are natural they are ascertainable. I will search for them." So he set about the task with the result that all the world knows. He discovered the process called by him natural selection, and saw it to be a real cause in the generation of species.
Now comes the greatly important point. I have said Darwin carried the evolution idea into the second of three stages through which interpretations of the world usually run; the stage, namely, of qualitative, discursive demonstration. Not having yet reached the third stage, that of quantitative demonstration, he had no way of measuring in a mathematical sense the efficiency of natural selection. He could establish no quantitative relation between cause and effect. In fact he did not look at the problem from the quantitative standpoint in the proper sense at all. So it was almost inevitable that he should exaggerate the power of the cause he had discovered. And see the essential nature of this exaggeration: Before Darwin supernatural causes were held to account for the origin of species. But supernatural causes are always adequate, final. Supernaturalist doctrines are always absolutist doctrines. Therefore effort to make natural selection supplant supernatural causation is effort to make it, too, adequate, final. Attempt to make natural selection the sole, the complete cause of evolution, and you become a finalist, an absolutist. In a word you retain the essence of supernaturalism. Absolutist natural selectionism is only a disguised
the misshapen legs, cloven feet, pendulous lips, and curiously mounded back of the sleepy beast, the old man turned away with the remark "there ain't no such animal!" I may be wrong as my sources of knowledge are limited, but I believe a considerable number of British naturalists will refuse to let Sir E. Ray take them with him into the class with the Jersey farmer.
