This week, at my alma mater Georgia Tech, I spoke to a group of student leaders in an organization that is dedicated to advancing the cause of Christ on campus. The purpose of my message was to equip the students with some intellectual tools for critiquing the philosophy of naturalism, which is prevalent on campus. Simply stated, naturalism holds that all that exists is natural, having properties that can be known through sense experience, and therefore all explanations of phenomena must be limited to natural causes. This post will summarize one of the arguments against naturalism I shared with the students.
The argument focuses on a naturalist view of evolutionary theory. As a scientific theory, evolution provides an explanation of the mechanism of species diversification. Built on ample empirical data from both the present and the past, it shows how species can change with time in response to changes in their environment (adaptation). The idea that this process of diversification driven by natural selection is random, unguided, and ultimately purposeless, though is not derived from science, but is a requirement of a naturalistic worldview. This ‘evolutionary naturalism’ is what opposes a biblical view of creation, and it is fraught with logical incoherence.
Esteemed philosopher Alvin Plantinga, in his 2011 book Where the Conflict Really Lies: Science, Religion, and Naturalism, argues that evolutionary naturalism is logically self-defeating (one of the most powerful arguments one can make against a theory is to show how it contradicts itself). The argument centers on the insightful question, “Is it likely that an unguided process, that only favors random changes in species when these changes enhance their survival, would produce cognitive equipment (i.e. neurological processes) that reliably form true beliefs?” Evolutionary naturalism says that the human brain, and accompanying sense organs, evolved in such a way as to confer survival advantages. So, in other words, does our brain’s ability to form true beliefs guarantee increased chances of survival?
Obviously, some true beliefs are useful for survival: knowing the truth about what is safe to eat and what animals see you as prey a certainly an advantage. But while true beliefs may be advantageous, is it necessary that advantageous beliefs be true? Simple reflection reveals that the answer is obviously no: one can think of countless examples of beliefs that can be useful, but not true. For example, imagine a primitive ancestor whose cognitive equipment forms the belief that baby alligators can eat people. This belief would cause him to not only avoid baby alligators, but in doing so also avoid the real predators: momma alligators! Or he could develop the beliefs that bright colored creatures are poisonous (e.g. poison frogs), and thus avoid death by poison, but of course some bright colored creatures are not poisonous, and some may even be good for food.
Some advantageous beliefs are true, others are false, but whether it is correct or not would just be accidental. Thus, Plantinga notes that ”while it is possible that any particular belief can be true, it is not necessary that any beliefs be true.” Consider the belief, then, in evolutionary naturalism itself (this is where the argument gets tricky, so get ready to ponder deeply!). This belief, by its own criteria, would have to be beneficial to survival, which means it might be true or it might be false – we should not be able to know if it’s true, just that’s useful. Since unguided evolution does not necessarily produce brains that reliably form true belief, then why should we trust that our belief in unguided evolution, which our brain produced, is true? This renders evolutionary naturalism self-defeating: if it was true, we would have no explanation for how we are able to know that ii is true. Or, as Plantinga asks, “If you have no good grounds for trusting your cognitive faculties as truth-oriented, why trust them regarding the truth of evolution?”
This problem perhaps is why Darwin himself echoed such doubts with his own theory:
With me the horrid doubt always arises whether the convictions of man’s mind, which has always been developed from the mind of lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?