Theism and Human Free Will

Friends and foes of the intuitive and commonsense view that humans have libertarian freedom of the will all agree that it is, on the face of it, incompatible with materialism. If the mind just is the brain and the brain just is a material object subject to the laws of physics, our thoughts and intentions would seem to be the result of causal forces which predate us and over which we have no control. Free will, on this view, is an illusion.

There are three points to note.

The first: John Searle has written that the experience of free will is so compelling that people cannot act as though it is an illusion even if it is one. Hoffman and Rosenkrantz, in another connection, have said something significant to the dispute. They take the view that if something belongs to a universal and commonsense ontology, “then there is a prima facie presumption in favour of its reality. Those who deny its existence assume the burden of proof.” Swinburne has formalised these ideas into a basic principle of epistemology which he calls The Principle of Credulity: We should, in the absence of compelling evidence to the contrary, believe that things are the way they seem to be.

The second: There is no such compelling evidence against the view that humans have libertarian freedom of the will. The laws of Quantum Theory, notes Swinburne, are probabilistic. And while, in general, indeterministic behaviour on the small scale averages out to produce deterministic behaviour on the large scale, “it is possible to have devices that multiply small-scale indeterminacies so that a small variation in the behaviour of one atom can have a large scale effect.” Consider, for instance, an atomic bomb designed to detonate if and only if a certain carbon 14 atom decays within an hour. This would qualify as a “multiplying system,” since it relays indeterminacy on the small scale into the large scale, while a block of radioactive carbon would be an “averaging system,” since it averages out indeterminacy on the small scale to produce determinacy on the large scale. The brain, notably, is the most complex physical system known to science. And because it, “causes conscious events and its states are caused by conscious events,” so, clearly, “laws of a very different kind govern the brain from those that govern all other physical states.” It is possible that the brain is a multiplying system rather than an averaging system. And for this reason, “it is widely believed that Quantum Theory rules out physical determinism.” [1]

The third and final point is of great relevance to the first. There is in principle no possible evidence that could produce a justified belief in determinism because free will is a prerequisite to the formation of justified belief of every kind—including justified belief in determinism itself. To understand this last point consider the plight of a neuroscientist who seeks to establish that determinism is true. To complete his task he must make observations, discern a pattern, formulate a generalisation and infer a theory. All this relies on rational adjudication, memory and intention. But if determinism is true, these mental operations and their results have no rational content. His belief in determinism is, ex hypothesi, not caused by the apprehension of reasons but produced by a brain state that is itself determined by extramental forces. Justified belief in determinism therefore requires that determinism is false and so suffers from self-referential incoherence.

It follows from the combination of all these points (the compelling experience of free will, the Principle of Credulity, the lack of evidence and the a priori impossibility of justified belief in determinism) that we are rationally obligated to affirm libertarian freedom of the will.

What is the relevance of all this to theism? Since the Bible teaches that God, an immaterial spirit, created man in his image, Abrahamic theists have a priori grounds for expecting certain properties that resist reduction to the material to be instantiated in man if God exists. It is no surprise on theism that our most novel and essential property, our mental life, should resist a materialistic explanation. [2] Free will, in particular, is provocatively suggestive of the imago dei since if man exercises libertarian causation he instantiates in miniature the principle of uncaused causation imputed to God in classical theism. [3]

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[1] Moreover, recent evidence appears to confirm that human beings exercise free will. As the British neuroscientist Chris Frith reported in a recent interview,

There is a slew of experiments around these days asking, “What happens to people if you tell them that they don’t have free will?” which you do by saying, “Francis Crick, who is the cleverest scientist around, wrote this thing saying, ‘All sensible people now know free will doesn’t exist.’” If you tell people they don’t have free will and they believe you then they are more likely to cheat on exams; they become more selfish. And, more compelling to me, is that their behaviour in reaction time tasks changes. Normally in reaction time tasks you slow down after you make an error (which is due to some monitoring of your behaviour in taking account of this) but you get less slowing down after being told that free will doesn’t exist—presumably because they have lost their faith in top-down control. And it even changes the amplitude of readiness potential in the brain, which of course was what Libbit was measuring in his famous anti-free will task. I think this is fascinating because basically, this is an example of top-down control, what people telling you influencing how your brain works, which is what free will is all about. So that telling people that they don’t have free will actually demonstrates that we do.

[2] For a discussion of all five mental properties that resist reduction to the physical, see here.

[3] See the Modal Cosmological Argument and the Kalam Cosmological Argument.

 

The Evolutionary Argument Against Naturalism

Our cognitive faculties include memory, perception and rational intuition. In science, as in every day life, these work together to produce beliefs. It is natural to assume that our cognitive faculties produce beliefs that are mostly true. But Alvin Plantinga has given a forceful argument that, on naturalism, [1] this assumption is unsafe.

Consider: The naturalist believes the mind “just is” the brain and so takes a belief to be something like a long-standing structure in the nervous system. The problem is that neurology can produce behaviours that increase fitness whether or not the beliefs annexed to that neurology are true. Survival, to be sure, does require cognitive devices that track crucial features of the environment and are appropriately connected to intention and muscular reflexes. That is not disputed. What is disputed is the necessary annexation between those cognitive devices and true beliefs. In fact, adaptive behaviour does not require true belief—or belief at all.

Think of an organism fleeing from a predator. Undoubtedly, its cognitive devices are tracking the predator and producing a useful response. But “tracking” itself is not belief and, so long as the neurology of the organism causes it to flee, the belief annexed to its neurology need not even contain a predator and it certainly need not be true. “It could be true,” says Plantinga, “it could be false; it doesn’t matter.”

Darwin himself was troubled by this. “With me the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy,” he wrote in a private correspondence. “Would any one trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?” The problem was also noticed by C. S. Lewis, the chemist J. B. S. Haldane [2] and atheist philosopher John Gray. “Modern humanism,” Gray writes, “is the faith that through science humankind can know the truth. But if Darwin’s theory of natural selection is true, this is impossible. The human mind serves evolutionary success, not truth.”

Plantinga’s argument applies to all beliefs but with a force that increases as beliefs become irrelevant to survival. Perception, for example, is especially relevant to feeding, fleeing, fighting and reproduction and so beliefs directly informed by perception may be taken to be more reliable. Beliefs about physics, aesthetics and philosophy, on the other hand, are irrelevant to survival. These must be regarded as far less reliable. Metaphysical beliefs, including both naturalism and theism, fall into this second category.

What then is the likelihood, on naturalism, that some belief p instantiated in an organism is true? Plantinga suggests that, since the alternatives seem about equiprobable, we should give it a probability of about a half. And what, in that case, is the probability that its cognitive faculties are generally reliable? Plantinga suggests we consider his cognitive faculties reliable if they generate true beliefs 45 percent of the time. He writes,

If I have one thousand independent beliefs, for example, the probability that three quarters or more of these beliefs are true will be less than 10–58. And even if I am running a modest epistemic establishment of only one hundred beliefs, the probability that three-quarters of them are true is very low—something like .000001

The rest of the argument follows by tautology: If I cannot trust my cognitive faculties, I cannot trust any belief they produce and especially not any metaphysical belief; but naturalism itself is a metaphysical belief produced by my cognitive faculties; therefore, I cannot trust naturalism. Plantinga concludes by saying that naturalism is self-referentially incoherent and cannot be rationally affirmed.

I think it is worth dwelling for a moment on the inescapable circularity of every possible objection to this argument: Any theory p which purports to prove the reliability of your cognitive faculties is itself a product of the cognitive faculties whose reliability it seeks to prove. Thomas Reid memorably analogised this problem by observing that, “If a man’s honesty were called into question, it would be ridiculous to refer to that man’s own word whether he be honest or not.” In a like case, Reid said, it is absurd to try and, “prove by reasoning that reason is not fallacious.”

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[1] Naturalism is a philosophical viewpoint entailed by atheism according to which everything arises from natural properties and causes and supernatural or spiritual explanations are excluded or discounted.

[2] Haldane complained that if the thoughts in his mind were just the motions of atoms in his brain (a physical object that has arisen by motiveless and unguided mechanisms) why should he believe anything his brain tells him—including the idea that his brain is made of atoms? Lewis, for his part, wrote,

If all that exists is Nature, the great mindless interlocking event, if our own deepest convictions are merely the by-products of an irrational process, then clearly there is not the slightest ground for supposing that our sense of fitness and our consequent faith in uniformity tell us anything about a reality external to ourselves. Our convictions are simply a fact about us—like the colour of our hair.