Hoyle said that the probability of life originating on Earth is no greater than the chance that a hurricane, sweeping through a scrapyard, would have the luck to assemble a Boeing 747. Others have borrowed the metaphor to refer to the later evolution of complex living bodies, where it has a spurious plausibility. The odds against assembling a fully functioning horse, beetle or ostrich by randomly shuffling its parts are up there in 747 territory. This, in a nutshell, is the creationist’s favourite argument – an argument that could be made only by somebody who doesn’t understand the first thing about natural selection: somebody who thinks natural selection is a theory of chance whereas – in the relevant sense of chance – it is the opposite.

The creationist misappropriation of the argument from improbability always takes the same general form, and it doesn’t make any difference if the creationist chooses to masquerade in the politically expedient fancy dress of ‘intelligent design’ (ID). Some observed phenomenon – often a living creature or one of its more complex organs, but it could be anything from a molecule up to the universe itself – is correctly extolled as statistically improbable. Sometimes the language of information theory is used: the Darwinian is challenged to explain the source of all the information Intelligent design has been unkindly described as creationism in a cheap tuxedo. in living matter, in the technical sense of information content as a measure of improbability or ‘surprise value’. Or the argument may invoke the economist’s hackneyed motto: there’s no such thing as a free lunch – and Darwinism is accused of trying to get something for nothing. In fact, as I shall show in this chapter, Darwinian natural selection is the only known solution to the otherwise unanswerable riddle of where the information comes from. It turns out to be the God Hypothesis that tries to get something for nothing. God tries to have his free lunch and be it too. However statistically improbable the entity you seek to explain by invoking a designer, the designer himself has got to be at least as improbable. God is the Ultimate Boeing 747.

The argument from improbability states that complex things could not have come about by chance. But many people define ‘come about by chance’ as a synonym for ‘come about in the absence of deliberate design’. Not surprisingly, therefore, they think improbability is evidence of design. Darwinian natural selection shows how wrong this is with respect to biological improbability. And although Darwinism may not be directly relevant to the inanimate world – cosmology, for example – it raises our consciousness in areas outside its original territory of biology.

A deep understanding of Darwinism teaches us to be wary of the easy assumption that design is the only alternative to chance, and teaches us to seek out graded ramps of slowly increasing complexity. Before Darwin, philosophers such as Hume understood that the improbability of life did not mean it had to be designed, but they couldn’t imagine the alternative. After Darwin, we all should feel, deep in our bones, suspicious of the very idea of design. The illusion of design is a trap that has caught us before, and Darwin should have immunized us by raising our consciousness.

Excerpted from page number 137-139 of ‘The God Delusion’ by Richard Dawkins