Lewis asserts that by this logic, the statement "I have reason to believe naturalism is valid" is self-referentially incoherent in the same manner as the sentence "One of the words of this sentence does not have the meaning that it appears to have", or the statement "I never tell the truth".[2] In each case, to assume the veracity of the conclusion would eliminate the possibility of valid grounds from which to reach it. To summarize the argument in the book, Lewis quotes J. B. S. Haldane who appeals to a similar line of reasoning. Haldane states "If my mental processes are determined wholly by the motions of atoms in my brain, I have no reason to suppose that my beliefs are true ... and hence I have no reason for supposing my brain to be composed of atoms."[3]