Charles Darwin

To see what changed in 1859 it helps to know what was being taught before it. William Paley's Natural Theology of 1802 opens with a man crossing a heath who finds a watch and concludes, from the fitting of its parts to a purpose, that it had a maker. Paley then works through the eye, the ear, the joints and the circulation of the blood, arguing at every step that the same inference holds and holds more strongly. This was not a fringe position. It was a set text at Cambridge, where Darwin read it as an undergraduate preparing for ordination, and he said later that he had been charmed by its logic.

Natural selection removes the inference without denying the observation. Organisms really are fitted to their conditions, sometimes exquisitely, and the fitting is real and needs an explanation; but heritable variation plus differential survival, over enough time, will produce it with no aim in view and nobody choosing. Darwin was careful about how far he pushed this. On the Origin of Species closes with a sentence about life having been breathed into a few forms or into one, and the argument nowhere requires atheism. What it does require is that adaptation stop being evidence, and that took the strongest natural argument for God then available out of service.

Darwin's own movement away from Christianity was gradual and he described it that way. He had trained for the clergy and had once not doubted the strict truth of the Bible; the disbelief crept in, on his account, at a rate so slow that he felt no distress at it. Two things weighed as heavily as the science. One was the difficulty of a benevolent design that includes suffering, which he raised again and again in letters. The other was the death of his daughter Annie in 1851. He settled on calling himself an agnostic, using the word his defender T. H. Huxley had coined, and declined the label of atheist.

The religious reception was never one reaction. Some Anglican and Catholic writers accepted evolution within a decade and read it as the manner of creation rather than its denial; others held the line at the special creation of the human soul; the fiercest organised resistance came later and elsewhere, in the American movement that produced the fundamentalist pamphlets after the First World War and the Scopes trial of 1925. That timing matters. The argument now heard in public is not the Victorian dispute resumed. It is a twentieth century American argument with a history of its own, and treating the two as one makes both harder to follow.