People who are active in apologetics often hear or read the opinions of various skeptics about how this or that skeptic was formerly Christian, but then they "wised up" or "learned better." This is consistent with the idea held by many people that a belief in God (or a god) is irrational because there is no evidence that such a god exists. Ignoring for a moment that a claim that "no evidence exists" stems from a failure to recognize the distinction between "evidence" and "proof", this position implies that it is possible to rationally infer the true state of affairs, i.e., that there is no God and that the universe is the end result of purely physical processes acting in a closed system. This view fails to recognize within itself a deep logical problem hidden beneath the surface. If the speaker is correct that there is no god and Materialism constitutes the explanation for the universe as we know it, then they are irrational to think so.
This past week, I was reading Victor Reppert’s fine book, C.S. Lewis’ Dangerous Idea, wherein he adopts and defends C.S. Lewis’ argument from reason. In the course of the book, he proposes a syllogism that argues that a belief in materialism ought to be rejected because it negates its own belief. While reading his arguments, it occurred to me that even if materialism is true, the belief "materialism is true" appears to be necessarily irrational.
A. Understanding Materialism
First, let me clarify the meaning of "Materialism." Materialism begins with the worldview that the universe is all that exists, and nothing exists beyond the universe. In other words, the universe is a closed causal system. This belief that the universe is everything leads to the view that everything that exists in the universe results from the application of physical processes on the basic materials in the universe, and those materials were themselves formed by the physical processes of the universe. For example, stars come together and act the way they act due to a combination of physical laws, chemistry, electromagnetism, etc. acting upon the star’s constituent elements (which themselves arose as the result of purely physical processes). When the star kicks off a solar flare, such a flare is the result of the combination of these physical processes acting on the star’s constituent elements.
Materialism, as a worldview, is akin to a religion. It is a belief that cannot be positively affirmed through scientific testing, but which serves as the basis for the entire understanding of the universe and how it works. While there are differing sects of Materialism, Victor Reppert identifies three traits that all sects of materialism share:
a. "The physical level is to be understood mechanistically."
b. "The physical order is causally closed."
c. "Given the state of the physical, there is only one way the mental can be."
B. Materialism and Rational Inference.
With this understanding of the basic traits of Materialism, we can reason that if Materialism is true, then the universe has no outside intelligence which imbued humanity with the ability to reason. Reason, or what we understand as reason (or more accurately, rational inference) arises solely from physical forces acting on our brains. Thinking is no more than (and cannot be more than) the end result of our brain cells interacting with and reacting to the electro-chemical occurrences in our brain. While the creation of a thought is much more complex than the creation of a solar flare, both can traced their genesis to purely physical processes.
If physical processes are all there is and explain the existence of all matter and how it acts, and if human beings are no more than evolved gatherings of physical cells that act as they do because of these physical processes, then everything about human beings, including their ability to engage in rational inference, is the end result of these natural processes and only these natural processes.
C. Two Syllogisms and a Hobson’s Choice
If it is true that human beings are merely the end result of a series of physical processes and that our perceived ability to engage in rational inference is the end result of those processes, then it leads to a Hobson’s choice for Materialists. The choice is shown by the following two Syllogisms.
Premise A: If Materialism is true then all beliefs can be fully explained in terms of non-rational causes.
Premise B: If all beliefs can be fully explained in terms of non-rational causes then no belief can be rationally inferred.
Conclusion 1: Therefore, if Materialism is true then no belief can be rationally inferred.
Premise D: “Materialism is true” is a belief.
Conclusion 2: Therefore, if Materialism is true then “Materialism is true” cannot be rationally inferred.
Premise F: If a person claims to have a rationally inferred belief that cannot be rationally inferred then such a belief is necessarily irrational.
Conclusion 3: If materialism is true, the belief that “Materialism is true” is necessarily irrational.
Premise G: If materialism is false, then beliefs are not necessarily explainable solely in terms of non-rational causes.
Premise H: If all beliefs are not necessarily explainable solely in terms of non-rational causes, then there is a possibility that a belief can be rationally inferred.
Premise I: “Materialism is true” is a belief.
Conclusion 4: If materialism is false, then there is a possibility that “Materialism is true” can be rationally inferred.
Both arguments (each of which is merely the converse of the second) depend on the truth of the statement “If Materialism is true then all beliefs can be fully explained in terms of non-rational causes.” Is this true? It seems to follow from the fact that Materialism posits that we are in a closed universe. If there is no outside intelligence that has imbued us with the ability to engage in rational inference, then what we call “rational inference” must be the result of the physical processes acting on our brain cells. In such circumstances, is there really such a thing as rationality, or is it more appropriate to say that the reason that a person has “rationally inferred” proposition X is because their in their present brain state they could not believe otherwise? I think that the argument that it must be the latter is very strong.
This raises the interesting question for Materialists: if Materialism is true then you may be right, but you could not arrive at that conclusion through rational inference and you have decided this issue irrationally. If Materialism is untrue, then you can at least rationally arrive at that conclusion even though you are wrong. Which is preferable?