C.S. Lewis held to many of the scientific conclusions of his day. Nonetheless, he was often critical of what others have sometimes called “scientism”—a worldview that treats science as a stand-alone teller of truth without a deeper epistemological basis and thus room for a metaphysics; a form of science that makes absolutist exclusive claims that lead it to assume more jurisdiction than its methodological parameters actually allow.

See the following quote from his lecture, “Is Theology Poetry?” or as we might rephrase it, Is Christianity nothing more than aesthetically pleasing mythology?

“The picture so often painted of Christians huddling together on an ever narrower strip of beach while the incoming tide of ‘Science’ mounts higher and higher corresponds to nothing in my own experience. That grand myth … is not for me a hostile novelty breaking in on my traditional beliefs. On the contrary, that cosmology is what I started from. Deepening distrust and final abandonment of it long preceded my conversion to Christianity. Long before I believed Theology to be true I had already decided that the popular scientific picture at any rate was false. One absolutely central inconsistency ruins it….

The whole picture professes to depend on inferences from observed facts. Unless inference is valid, the whole picture disappears. Unless we can be sure that reality in the remotest nebula or the remotest part obeys the thought laws of the human scientist here and now in his laboratory — in other words, unless Reason is an absolute — all is in ruins. Yet those who ask me to believe this world picture also ask me to believe that Reason is simply the unforeseen and unintended by-product of mindless matter at one stage of its endless and aimless becoming.

Here is flat contradiction. They ask me at the same moment to accept a conclusion and to discredit the only testimony on which that conclusion can be based. The difficulty is to me a fatal one; and the fact that when you put it to many scientists, far from having an answer, they seem not even to understand what the difficulty is, assures me that I have not found a mare’s nest but detected a radical disease in their whole mode of thought from the very beginning. The man who has once understood the situation is compelled henceforth to regard the scientific cosmology as being, in principle, a myth; though no doubt a great many true particulars have been worked into it.