Scientism is the view that the only things that can be known are things that can be discovered through science. That’s a very popular view, but there are at least three things wrong with it.

First, Tough Questions Answered quotes philosopher Ed Feser, who says that the enterprise of science makes assumptions that cannot be justified by science itself.

Feser writes:

Of its very nature, scientific investigation takes for granted such assumptions as that: there is a physical world existing independently of our minds; this world is characterized by various objective patterns and regularities; our senses are at least partially reliable sources of information about this world; there are objective laws of logic and mathematics that apply to the objective world outside our minds; our cognitive powers – of concept-formation, reasoning from premises to a conclusion, and so forth – afford us a grasp of these laws and can reliably take us from evidence derived from the senses to conclusions about the physical world; the language we use can adequately express truths about these laws and about the external world; and so on and so on.

Science assumes that those things are true, it cannot discover them.

Second, scientism cannot account for things we know apart from science.

William Lane Craig explains:

First, scientism is too restrictive a theory of knowledge. It would, if adopted, compel us to abandon wide swaths of what most of us take to be fields of human knowledge. Your friend admits this with regard to moral and aesthetic truths. On his view there is nothing good or evil, right or wrong, beautiful or ugly. But is it plausible to think that there are no aesthetic or moral truths? On your friend’s view there’s nothing wrong with torturing a little girl to death. Why should we accept such a conclusion simply because of a epistemological restriction? Isn’t this a signal that we need rather to broaden the scope of our theory so as to encompass other types of knowledge? Your friend says he will treat logical and mathematical truths as merely empirical truths. Good luck! Truths like “If p implies q, and p, then q” or “2 + 2 = 4” are to all appearances necessary truths, not merely empirical generalizations.

Third, scientism is self-refuting.

William Lane Craig explains:

Secondly, scientism is self-refuting. Scientism tells us that we should not believe any proposition that cannot be scientifically proven. But what about that very proposition itself? It cannot itself be scientifically proven. Therefore we should not believe it. Scientism thus defeats itself.

You can’t prove scientism (a theory of what we can know) using science. It refutes itself.

So, there are three reasons to reject scientism. Nothing I have said here should be taken as criticism of science, though. On the contrary – the progress of science is one of the best friends of Christian theists. We have gained a lot from the advances made by science in areas like cosmology, cosmic fine-tuning, the origin of life, the fossil record, and astrobiology. We love science. But scientism is false.