Religion and epistemology
Authors: Plantinga Alvin , Bergmann Michael 
Published: September 2018

Epistemology is theory of knowledge; one would therefore expect epistemological discussions of religion to concentrate on the question as to whether one could have knowledge of religious beliefs. However, discussions of religious belief have tended to focus on arguments for and against the existence of God: the traditional theistic arguments on the one hand and, on the other, such arguments against the existence of God as the argument from evil.
To see why, we must think about theistic evidentialism, the doctrine that, in order to be rationally justified, theistic beliefs must be based on propositional evidence: evidence from other things one believes, evidence that can be put forward in the form of argument. And going with theistic evidentialism is the evidentialist objection to religious belief: the objection that religious belief is unjustified because there is not enough propositional evidence for it. Theistic evidentialism, which insists that propositional evidence is required for the justification of religious belief, should be distinguished from evidentialism in epistemology, which is a more general theory, according to which a belief is justified only if it is based on evidence of some kind – either propositional evidence consisting of other beliefs or nonpropositional evidence consisting of mental states that are not beliefs, for example, perceptual experiences.
Theistic evidentialism begins with the classical foundationalists René Descartes and (especially) John Locke. According to Descartes and Locke, some beliefs are certain for us. There are two kinds of certain belief: first, self-evident beliefs, such as ‘2 + 1 = 3’, and second, beliefs about one’s own mental life, such as ‘it now seems to me that I see a hand’. According to Locke, I am, of course, clearly justified in accepting those beliefs that are certain; indeed, it is not within my power to reject them. For any belief that is not certain, however, I am justified in accepting it only if I can see that it is probable or likely with respect to beliefs that are certain for me.
What is this ‘justification’ and why does it matter whether or not my beliefs have it? Locke believed that human beings are rational creatures, who have an intellectual duty to believe only those propositions that they can see to be probable with respect to beliefs that are certain for them. Justification is simply the condition of being within your rights, of not having gone against your duties.
Locke’s view has been extremely influential among epistemologists. Furthermore, given his views, it is easy to see why there should be so much concern with proofs or arguments for the existence of God. It is not self-evident that God exists and the belief that God exists is not about one’s own mental life. But then, according to this Lockean way of thinking, anyone who accepts this belief must see that it is probable with respect to what is certain for them, else they will be going contrary to their duty. Proofs or arguments are just the vehicles by means of which one establishes that a given belief is probable with respect to what is certain.
Classical foundationalism has come to seem less compelling. First, the history of Western philosophy from Descartes to Hume shows that, if we are rationally permitted to believe only propositions that are probable with respect to what is certain, then most of what we believe – that there is an external world, that there are other people, that there has been a past – will not be justified. Second, on reflection it just does not seem that there really is a duty to restrict belief to what is probable with respect to what is certain.
More broadly, we can distinguish two different kinds of objections to religious belief. First, there is the claim that religious belief is not true. Such an objection may be termed a de facto objection: it is a claim about the facts. The second type of claim is not that religious belief is false, but that, whether or not it is false, it is in some way improper – unjustified, irrational or otherwise unworthy of belief. The evidentialist objection to religious belief is the most prominent version of such a de jure criticism of religious belief. But there is another de jure objection that has become increasingly important. This is the objection, raised by Freud, Marx and Nietzsche, that religious belief is irrational in a different, nonevidential sense. According to Freud, religious belief arises out of wish fulfilment: we find ourselves confronted by a cruel and heartless nature that delivers pain, fear and hurt, and in the end demands our death. As a response, we (subconsciously) invent a father in heaven who loves us and is really in charge of nature. The reason why this constitutes a criticism of such belief is that this mechanism of illusion is not aimed at the production of true belief, but rather at belief that has some other, nontruth-related property – in this case, the property of enabling us to carry on in this otherwise discouraging world. It is for this reason that religious belief, on this account, is irrational.
Perhaps the most important thing to see about this criticism is that, while it is an allegedly de jure objection to religious belief, it is not really independent of the de facto question. If Christianity is true, for example, then Christian belief clearly is not irrational in Freud’s sense. If it is true, then there is such a person as God, who intends that we should have knowledge of him; and the cognitive processes that produce belief in God very likely have as their function the production of true belief in us. On the other hand, if Christianity is false, then it is very likely that Christian belief is not produced by cognitive processes whose purpose it is to produce true belief. Therefore this de jure criticism of religious belief presupposes that religious belief is false.
Two other challenges to religious belief are due to the problem of religious disagreement with epistemic equals or peers and the worry that evolutionary accounts of the origins of religious belief undermine it. To respond to the first challenge, it is important to consider more carefully what qualifies one as an epistemic peer, incorporating into an account of peerhood other factors besides a person’s intelligence. To respond to the second, it helps if the broader religious worldview is one according to which God guided the evolutionary processes that gave rise to religious belief and, furthermore, contributed to the formation of religious belief through special revelation.