The claim that “No statement is rational to believe,” is self-defeating, since it implies that the claim itself is not rational to believe. In this article I’ll argue that the view that we have no free will undermines rationality, and so undercuts itself, albeit in a somewhat indirect way. The following quote from J.B.S. Haldane (1892-1964) has some relevance to this matter, since if we have no free will then our thoughts and beliefs are determined by physical processes:
It seems to me immensely unlikely that mind is a mere by-product of matter. For if my mental processes are determined wholly by the motions of atoms in my brain, I have no reason to suppose that my beliefs are true….And hence I have no reason for supposing my brain to be composed of atoms.In philosophy, the view that all our thoughts, actions, and beliefs are determined by processes outside our control and that we have no free will is called hard determinism. This is contrast to soft determinism, which affirms determinism but also claims we are in fact responsible for our behavior (I attacked soft determinism, also known as compatibilism, in The Free Will Argument for the Soul). Hard determinism says that we are never responsible for any of our thoughts and beliefs, and it is my contention that this view undermines human rationality.
Ways to Believe
There are at least two ways we can arrive at a belief or course of action. We can decide to do something or accept some belief via reasons that are freely chosen, or our actions and beliefs can be the result of unthinking and impersonal causes of which we have no control over. To illustrate the idea of freely chosen reasons, suppose I have libertarian free will with respect to two options before me: fattening chocolate ice cream and low-fat strawberry frozen yogurt. Both have a reason for me to eat it: for the fattening chocolate ice cream, it tastes better; for the low-fat frozen yogurt, it’s more healthful. Both options are live and available to me, but I freely choose the low-fat frozen yogurt with my reason being “it's better for me.” Nonetheless, that reason is freely chosen. To illustrate the idea of unthinking and impersonal causes, suppose a man believes a certain economic policy is the best one because a strange brain tumor is causing him to think so.
With free will, we are ultimately responsible for our actions, and this at least allows the possibility for our thoughts and beliefs to be the product of our own rational thought (as via freely chosen reasons). In contrast, hard determinism implies that all our thoughts and beliefs are ultimately caused by unthinking and impersonal causes, if for no other reason that all our behavior is ultimately caused by forces outside of ourselves and that we ourselves are never responsible for any of our thoughts and beliefs. Even if we ignore outside forces though, it seems to me that if our minds are purely physical then our mental processes would be wholly the product of (unthinking) atoms in motion. Such beliefs could be true or they could be false, but ultimately such beliefs would not be the product of rational thought but of mindless chemical reactions. Human rationality itself would be undermined, and our beliefs would be no more rational than a toothache.
The Calculator Reply
One of the best rebuttals to this sort of argument I can think of is something I’ll call “the calculator reply.” The calculator is a deterministic system, yet it provides answers in accord with reason. Similarly, our brains are like (albeit imperfect) calculators in that even though they are deterministic, they supply us with rationality.
One thing to remember is this: the claim is not that determinism entails that our beliefs aren’t mostly correct. Rather, the claim is that even if our beliefs are correct, we are not being rational in accepting them. Recall that under hard determinism, mindless and blind physical causes produce all our beliefs, rather than a mind having some control in producing them. Does the calculator argument compensate this to provide us with rationality? Consider this hypothetical set if scenarios in which astronauts find an alien species that mindlessly accepts any belief given to them. Also suppose we separate these aliens into groups A and B.
Scenario 1: We write down mathematical statements on slips of paper and give them to the aliens in the following manner: we give group A slips of paper that convey false beliefs like “2 + 2 = 5,” and also via paper slips we give group B true mathematical beliefs (having their source in rational individuals like ourselves) like “2 + 2 = 4.” Is group B more rational than group A? No, both are accepting beliefs thoughtlessly and without one iota of rational reflection.
Scenario 2: Suppose we give group A calculators that consistently give incorrect answers such as “2 + 2 = 5” and group B calculators that produce consistently correct answers. Both groups mindlessly accept the answers the calculators give them. Is group B being more rational than group A in accepting their beliefs? Again, the answer is no.
Scenario 3: Now suppose we implant the calculators within the heads of the aliens where their little head tentacles press the buttons and the calculators feed them the answers through neurochemical reactions. Group A is given the faulty calculators and group B is given the good calculators. Once again, both groups mindlessly accept whatever beliefs are given to them by these calculators. Not much has changed here other than the physical location of the calculators, so is group B behaving more rationally than group A? I think again the answer is no.
We can present the argument more formally as follows, where the if-then statement in premise (4) uses the material conditional.
|(1)||In scenario 1, group B is no more rational than group A.|
|(2)||In scenario 2, group B is no more rational than group A.|
|(3)||In scenario 3, group B is no more rational than group A.|
|(4)||If (1), (2), and (3) are true, then on hard determinism one’s brain operating in accord with reason is not a sufficient condition for genuine rationality.|
|(5)||Conclusion: on hard determinism, one’s brain operating in accord with the reason is not a sufficient condition for genuine rationality.|
Again, (4) is using the material conditional, which means the only way it can be false is if (1), (2), and (3) are true and one’s brain operating in accord with reason is not a sufficient condition for genuine rationality is false.
Here’s the reasoning behind premise (4): We can give aliens slips of paper whose answers are in accord with reason, but if they are mindlessly accepting whatever beliefs are presented to them, then it isn’t real rationality. Similarly, it seems that chemical reactions doing the same sort of thing to the group B aliens (whether in the manner specified in Scenario 3 or a more organic calculator integrated into the brain), then it isn’t real rationality. Making the calculators an organic part of the brain for the aliens in groups A and B doesn’t seem to make a relevant difference in making group B more rational than group A. If that’s true, then a brain operating in accord with reason is not a sufficient condition for genuine rationality.
The above deductive argument is logically valid, which means the conclusion follows necessarily from the premises by the rules of logic, and so a false conclusion requires a false premise. But all the premises seem to be true, and if so then the conclusion is true.
It is metaphysically possible for hard determinism to be true and for us to have correct beliefs. Yet even if we had consistently correct beliefs, hard determinism still undermines rationality. We simply have no reason to accept our beliefs as true if they are all solely the product mindless, blind physical causes.
It’s important to note what I am not arguing for in this article. The argument is not that if hard determinism is true, then our beliefs are mostly false. Rather, the argument is that if hard determinism is true, human rationality doesn’t exist. Our beliefs could still be true, but we wouldn’t be rational in accepting them any more than our hypothetical aliens are. We thus have the following sort of argument against hard determinism.
- If hard determinism is true, then human rationality does not exist.
- Human rationality does exist.
- Therefore, hard determinism is false.
 J.B.S. Haldane, Possible Worlds and Other Papers (New York: Harper & Brothers, 1928) p. 220.
 This of course wouldn’t apply if a theistic God designs our cognitive faculties to work a certain way to give us beliefs, in which case our thoughts are determined by a thinking mind (viz. the mind of God). In this case I’m referring to a version of hard determinism that assumes naturalism, where there is no supernatural mind guiding the development of our cognitive faculties, so that the external forces that produce our thoughts are mindless and impersonal. Note that the problem of our thoughts and beliefs ultimately being the product of mindless and impersonal causes is not resolved by our brains being the product of a purely physical creator if this creator’s thoughts and beliefs were itself the product of mindless and impersonal causes, since in that case our thoughts and beliefs would still (ultimately) be the result of mindless and impersonal causes.