Richard Lewontin, a well known geneticist and evolutionist from Harvard University, admits that he is "a materialist first, a scientist second":
It is not that the methods and institutions of science somehow compel us accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations, no matter how counter-intuitive, no matter how mystifying to the uninitiated. Moreover, that materialism is absolute, so we cannot allow a Divine Foot in the door.19
The term a priori that Lewontin uses is particularly significant. This philosophical term expresses a given assumption, based on no experimental data. In the absence of any information regarding the truth of an idea, that idea is assumed to be true, "from the beginning." As openly stated by the evolutionist Lewontin, materialism is an a priori assumption for evolutionists, one into which they attempt to make science fit.
Since materialism necessitates the rejection of a Creator, they cling to the theory of evolution as the only remaining alternative. It makes no difference how much the scientific findings refute evolution, since the scientists in question already regard evolution as a fact, a priori. This biased attitude leads to the belief that "unconscious substances can regulate themselves," which is a violation of both science and reason.19. Richard Lewontin, "Billions and billions of demons," The New York Review, January 9, 1997, p. 31.