The longer you ponder materialism, the graver the difficulties that present themselves. How can materialism account for the fact that we consider our accounts of the world to be not merely chemically generated reactions but true beliefs? British biologist J. B. S. Haldane sums up the problem: “If my mental processes are determined wholly by the motions of atoms in my brain, I have no reason to suppose my beliefs are true… and hence I have no reason for supposing my brain to be composed of atoms.” Physicist Stephen Hawking takes upthe horns of this dilemma and finds himself impaled:

“Now if you believe that the universe is not arbitrary, but is governed by definite laws, you ultimately have to combine the partial theories in science into a complete unified theory that will describe everything in the universe. But there is a fundamental paradox in the search for such a complete unified theory. Our ideas about scientific theories … assume we are rational beings who are free to observe the universe as we want and to draw logical deductions from what we see. In such a scheme it is reasonable to suppose that we might progress ever closer toward the laws that govern our universe. Yet if there really is a complete unified theory, it would also presumably determine our actions. And so the theory itself would determine the outcome of our search for it! And why should it determine that we come to the right conclusions from the evidence? Might it not equally well determine that we draw the wrong conclusion?”

Here is Hawking’s solution:

“The only answer I can give to this problem is based on Darwin’s principle of natural selection. The idea is that in any population of self-reproducing organisms, there will be variations in the genetic material and upbringing that different individuals have. These differences will mean that some individuals are better able than others to draw the right conclusions about the world around them and act accordingly. These individuals will be more likely to survive and reproduce and so their pattern of behavior and thought will come to dominate.”

Hawking’s solution is based on a non sequitur. Biologists invoke evolution to explain the challenges primitive man faced in prehistoric environments. But evolution cannot explain more than this. There were no survival pressures that required man to develop the capacity to understand the rotation of the planets or the microscopic content of matter. Moreover, evolution selects only for reproduction and survival, not for truth. Based on evolution, our ideas may be considered useful to us, but there are no grounds for presuming that they correspond with truth. Indeed, a useful lie is preferable to a truth that plays no role in genetic self-perpetuation. In reducing everything to the laws of nature we risk denying that there is any rationality or truth behind nature’s laws.

Perhaps the strongest argument against materialism is the argument from free will. Let me illustrate. I am sitting at my computer with a cup of coffee on my desk. I can reach over and take a sip if I choose; I can knock the coffee mug onto the carpet if I choose; I can just leave the cup alone and let the coffee get cold. Now I ask: is there anything in the laws of physics that forces me do any of these things? Obviously not. In Milton Friedman’s phrase, I am “free to choose.” This freedom characterizes many, although not all, of the actions in my life. I am not free to stop breathing while I am asleep, nor am I free to control the passage of food through my intestines. I am, however, free to knock my coffee mug onto the floor. Now once I decide to do this, and actually do it, then the trajectory of the coffee cup’s descent is entirely determined by the laws of physics. My choice to send it on that trajectory, however, is determined by no scientific law but rather by my free decision.