Most theistic evolutionists do not challenge either the conclusions of evolutionary biology or its naturalistic methodology, but argue merely that evolution by natural processes is compatible with theistic religion. To the extent that they go farther, and postulate a supernatural directing force in evolution, they violate the rules of methodological naturalism and are no more welcome in scientific discussions than outright creationists. For a productive scientific conversation to be even conceivable there would have to be a new force in the picture, one which is capable of entering the debate with arguments which the naturalists cannot easily refuse to take seriously. Unless we have a priori knowledge that naturalism is true, then we cannot rule out the possibility that supernatural action may have affected the history of life, and that evidence of that action may exist. Ratzsch similarly rejects Richard Dawkins' argument that reference to a creator in science as the source of biological complexity is logically pernicious because it leaves the creator unexplained.
Every explanation has an unexplained starting point.
On the other hand, if there are such gaps, refusing in principle to recognize them will equally get us off the track. This endorsement of a level playing field is more radical than readers may suppose. The view that science and methodological naturalism are inseparable is widespread among many scientists and philosophers, including theistic evolutionists, and makes it impossible for them to take seriously the possibility that the creation of genetic information might require intelligence. Show them a computer program and they will never question the need for a programmer. Show them a much more impressive example of design in nature, and they will never doubt that unintelligent material processes must have been responsible for the appearance of design.