The Darwinian Revolution

The publication in 1859 of The Origin of Species by Charles Darwin ushered in a new era in the intellectual history of humanity. Darwin is deservedly given credit for the theory of biological evolution: he accumulated evidence demonstrating that organisms evolve and discovered the process, natural selection, by which they evolve. But the import of Darwin's achievement is that it completed the Copernican revolution initiated three centuries earlier, and thereby radically changed our conception of the universe and the place of humanity in it.

The discoveries of Copernicus, Kepler, Galileo, and Newton in the sixteenth and seventeenth centuries, had gradually ushered in the notion that the workings of the universe could be explained by human reason. It was shown that the earth is not the center of the universe, but a small planet rotating around an average star; that the universe is immense in space and in time; and that the motions of the planets around the sun can be explained by the same simple laws that account for the motion of physical objects on our planet. These and other discoveries greatly expanded human knowledge, but the intellectual revolution these scientists brought about was more fundamental: a commitment to the postulate that the universe obeys immanent laws that account for natural phenomena. The workings of the universe were brought into the realm of science: explanation through natural laws. Physical phenomena could be accounted for whenever the causes were adequately known.

Darwin completed the Copernican revolution by drawing out for biology the notion of nature as a lawful system of matter in motion. The adaptations and diversity of organisms, the origin of novel and highly organized forms, even the origin of humanity itself could now be explained by an orderly process of change governed by natural laws.

The origin of organisms and their marvelous adaptations were, however, either left unexplained or attributed to the design of an omniscient Creator. God had created the birds and bees, the fish and corals, the trees in the forest, and best of all, man. God had given us eyes so that we might see, and He had provided fish with gills to breathe in water. Philosophers and theologians argued that the functional design of organisms manifests the existence of an all-wise Creator. Wherever there is design, there is a designer; the existence of a watch evinces the existence of a watchmaker.

The English theologian William Paley in his Natural Theology (1802) elaborated the argument-from-design as forceful demonstration of the existence of the Creator. The functional design of the human eye, argued Paley, provided conclusive evidence of an all-wise Creator. It would be absurd to suppose, he wrote, that the human eye by mere chance "should have consisted, first, of a series of transparent lenses ... secondly of a black cloth or canvas spread out behind these lenses so as to receive the image formed by pencils of light transmitted through them, and placed at the precise geometrical distance at which, and at which alone, a distinct image could be formed ... thirdly of a large nerve communicating between this membrane and the brain." The Bridgewater Treatises, published between 1833 and 1840, were written by eminent scientists and philosophers to set forth "the Power, Wisdom, and Goodness of God as manifested in the Creation." The structure and mechanisms of man's hand were, for example, cited as incontrovertible evidence that the hand had been designed by the same omniscient Power that had created the world.

The advances of physical science had thus driven humanity's conception of the universe to a split-personality state of affairs, which persisted well into the mid-nineteenth century. Scientific explanations, derived from natural laws, dominated the world of nonliving matter, on the earth as well as in the heavens. Supernatural explanations, depending on the unfathomable deeds of the Creator, accounted for the origin and configuration of living creatures—the most diversified, complex, and interesting realities of the world. It was Darwin's genius to resolve this conceptual schizophrenia.

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