Natural Theology and Creationism
By Darwin's time, the most influential account of the older worldview was the best-selling book Natural Theology, written by the Reverend William Paley and published in 1802. Paley began his work by reiterating the longstanding argument that various characteristics about God could be read off or inferred from the natural world — in the same way that one could ascertain features of a watchmaker by looking at the mechanism of a watch. For Paley the order evident within the natural world was testimony to a wise and benevolent deity, who had created a harmonious world that was much more intricate than any machine that could be created or imagined by humans. The organs of humans and animals were perfectly designed to play their part (i.e. eyes to see, the heart to pump blood), and the structures of organisms and the functions of their parts had been perfectly aligned since the Creation. Paley concentrated mainly on the extraordinary anatomical features that differed between species, and which allowed individuals in that species to live, and thrive in their particular environments. These features had been designed by God so as to give pleasure to creatures, and it was, he said, 'a happy world after all'.
Natural Theology was written at a time when belief in the divinely saturated world that Paley described was coming under threat. Indeed, he wrote the work to counter the corrosive effects of arguments by writers such as David Hume, Erasmus Darwin (Charles's grandfather), and Thomas Malthus that were current by 1800. Hume argued that the design argument was logically fallacious and merely resulted from humans imposing their own limited conceptions on the natural world — that there was no necessary connection between the watchmaker argument and the design argument. Erasmus Darwin put forward a radical evolutionary view of the world according to which life had existed for millions of years, starting with simple forms that grew more complex over time by dint of their own efforts ('improved by [their] own inherent activity').
Malthus, like Paley a cleric in the Church of England, had painted a bleak account of the effects of population pressures caused by the overly large amounts of progeny produced by the lowest orders of society. The fact of this tendency to overpopulation led to what he termed positive checks (in the form of disease, poverty and famine) that would always place breaks on populations. For Malthus this gave rise to terrible suffering, an evil blight on the world that nevertheless acted as a stimulus to humans to develop new ways of restricting population growth or of looking after the poor and sick.
The modern version of natural theology is called 'creationism'. Depending on their particular faith, 'Creationists' believe in the literal truth of the Koran, the Hebrew Bible (Old Testament) or the New Testament — and hold that the earth was created a few thousand years ago. Jewish and Christian Creationists, for example, understand the account of creation in Genesis to be literally true, giving an approximate date for the Creation of 4000 BCE (Before the Common Era). As well as taking literally the Scriptural account of Creation, modern creationists argue that every aspect of every organism is the way that it is because God, the benign and intelligent Creator, decreed that it would be so. A more sophisticated version of creationism, 'intelligent design', is described below.
In a post-Darwinian world, many scientists continue to be practising Christians, Jews, Muslims or Hindus, and see nothing incompatible in doing so. How one harmonises these two attitudes differs from one individual to the next, but one common tactic is to say that the Bible, for example, was only meant to refer to moral and religious questions, and that those passages that refer to the natural world should be ignored, or taken metaphorically. Or one might say that evolution by natural selection, a theory that effectively removes God from the history of life on Earth, does not remove God entirely but merely pushes his contribution back to the Creation. After he had created his wonderful work, he did not need to intervene.
The idea that the natural world itself is worthy of our reverence, a doctrine called 'pantheism', is also commonly held by a number of people. Many environmentalists, for example, have rejected institutional religions but believe that the astonishing majesty of the world around us is worthy of being revered. Darwin himself concluded the first edition of the Origin by stating: 'There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.' This strongly implies that he had renounced his Christian faith by the time he wrote his great work, but in the final five editions (of six in all) of his work he assed the key expression 'by the Creator' after the word 'breathed'.