Is Faith Rational?

What Is the Question?

The question whether faith is rational has been asked for as long as faith and reason have been distinguished. The answer depends on two prior questions. What is faith? Is it a kind of belief, a kind of trust, a virtue, a practice, or something else? And what is rationality? Is it the proportioning of belief to evidence, the avoidance of epistemic circularity, the formation of beliefs by reliable processes, or the responsiveness to reasons of various kinds? Until these are settled, the headline question floats free, and the disputants talk past each other.

The SEP entry on religious epistemology sets the contemporary debate as a contest between evidentialism, which holds that theistic belief is rational only if supported by adequate propositional evidence, and Reformed epistemology, which holds that theistic belief can be "properly basic," rational without inferential evidence if produced by a reliable mechanism. The two views turn on different theories of rationality, and the disagreement reaches into the foundations of epistemology.

Historical Background

The medieval scholastics treated faith and reason as complementary. Augustine said "crede ut intelligas," "believe that you may understand," treating faith as a precondition of insight. Aquinas distinguished the truths of reason, which philosophy can reach, from the truths of faith, which exceed reason but are not contrary to it, and which we accept on the authority of God revealing. Faith, for Aquinas, is an intellectual virtue, a habit of assent to what God has revealed, grounded in the credibility of the revelation and ultimately in God. The medieval synthesis held that faith is rational because revelation is credible, and because reason can show that God exists and that it is reasonable to trust God's word.

The Enlightenment fractured the synthesis. Hume and Kant challenged both the arguments of natural theology and the credibility of revelation, and the modern evidentialist tradition, running through Clifford's "ethics of belief," held that belief without sufficient evidence is a violation of epistemic duty. Clifford's dictum, "it is wrong always, everywhere, and for anyone, to believe upon insufficient evidence," is the modern statement of the case against faith. William James replied in The Will to Believe that there are cases, including the moral and religious cases, where we must choose without sufficient evidence and where such choosing is rational, even epistemically permissible.

Blaise Pascal, writing in the seventeenth century, gave the debate its sharpest practical turn. Pascal held that the existence of God cannot be proved or disproved, and that in the face of this uncertainty, the practical rationality of belief is governed by the expected utility of the bet. Pascal's Wager tries to show that, given the infinite payoff of eternal life and the finite cost of religious practice, the rational agent should bet on God. The Wager is a defense of the practical rationality of faith, even when its theoretical rationality is in doubt.

Evidentialism

The evidentialist tradition, dominant in analytic philosophy of religion from the mid-twentieth century, holds that theistic belief is rational only if supported by adequate propositional evidence. The evidence can be theistic proofs, the cumulative case from natural theology, religious experience, or historical testimony, but the belief must be inferentially grounded. Without such evidence, the belief is irrational, even if it is sincere, and even if it produces good fruits.

The evidentialist's strongest argument is that the alternative is a license for credulity. If belief can be rational without evidence, then any belief can be rational, including contradictory ones. The Mormon and the Muslim, the cargo cultist and the Catholic, would all be rational in their incompatible beliefs, which seems absurd. The evidentialist insists that the way to sort the wheat from the chaff is to demand evidence proportioned to the claim, and that the evidence for theism, while not negligible, falls short of what the claim requires.

The evidentialist tradition has produced serious theists as well as atheists. Richard Swinburne applies Bayesian probability theory to the theistic arguments and argues that the cumulative case, while no single argument is conclusive, raises the probability of theism above 0.5. Swinburne is an evidentialist who believes the evidence is sufficient. The contemporary evidentialist debate is largely between Swinburne and his critics, and between theists who accept the evidentialist framework and those who reject it.

Reformed Epistemology

The Reformed epistemology tradition, developed by Alvin Plantinga and Nicholas Wolterstorff since the 1980s, rejects the evidentialist demand. Plantinga's central claim is that theistic belief can be "properly basic," rational without being inferred from other beliefs, if it is produced by a reliable belief-forming mechanism. The model Plantinga develops, in the Warrant trilogy, is that God has designed human beings with a sensus divinitatis, a faculty that, in appropriate circumstances, produces belief in God. When the believer reads the stars, or feels guilt, or experiences beauty, the sensus divinitatis produces the belief that there is a God, and the belief has warrant, the property that turns true belief into knowledge.

The Reformed epistemologist's reply to the credulity worry is that not any belief can be properly basic, only beliefs produced by reliable mechanisms, and that the question whether the sensus divinitatis is reliable is the question whether theism is true. The Reformed epistemologist does not claim that all religious belief is rational, only that theistic belief can be, and that the evidentialist demand for inferential evidence is not a neutral constraint but a substantive epistemological thesis that itself needs defense.

Critics have raised several objections. The most powerful is the "great pumpkin" objection, raised by Plantinga himself in a self-critical moment: if the sensus divinitatis can make theistic belief properly basic, why cannot a "great pumpkin" sensus make belief in the great pumpkin properly basic? Plantinga's reply, developed over many years, is that proper basicality must be tested reflectively, by checking whether the alleged mechanism is reliable, whether the beliefs it produces cohere with our other knowledge, and whether the resulting epistemology is plausible. The test is not decisive, but it is not vacuous either. See the companion entry on reformed epistemology for the full argument.

Pascal's Wager and Practical Rationality

Pascal's Wager is the third path. Pascal held that the existence of God cannot be proved, and that in the face of agnosticism about proof, the practical rationality of belief is governed by the expected utility of the bet. If God exists and the believer gains eternal life, the payoff is infinite; if God does not exist, the believer has lost a finite cost, the inconveniences of religious practice. The expected utility of betting on God, Pascal argued, is infinite, and so the rational agent should bet on God.

The Wager has been criticized on many grounds. The "many gods" objection asks which God to bet on, since several religions promise infinite payoff. The "insincere belief" objection asks whether one can choose to believe, since belief is not under the direct control of the will. Pascal's reply is that one can choose to act as a believer, to attend mass, to use the holy water, and that the actions will, in time, produce the belief. The Wager is a defense of practical rationality that bypasses the question of theoretical proof, and it remains a live, if controversial, option in the debate.

Faith as Trust and as Virtue

A fourth tradition treats faith not as belief but as trust, and asks whether trust can be rational even when belief is not. The tradition runs from Kierkegaard, who held that faith is a leap beyond evidence into a personal relation with the divine, through the theologian Karl Barth, to contemporary virtue epistemologists who treat faith as an intellectual virtue, a disposition to trust responsibly. On this view, the question whether faith is rational is the question whether trust can be rational, and the answer is yes, when the trust is proportioned to the testimony and the relationship, and when it is open to correction.

Contemporary Relevance

The debate is live. The evidentialist tradition continues in the work of philosophers such as Paul Draper and J. L. Schellenberg, who argue that the evidence, including the fact of divine hiddenness, counts against theism. Reformed epistemology continues in the work of Plantinga's students and successors. The wager tradition continues in the work of philosophers who defend practical rationality against the dominance of theoretical proof.

The deeper question is what rationality itself is. If rationality is the proportioning of belief to evidence, evidentialism follows. If rationality is the formation of beliefs by reliable processes, Reformed epistemology follows. If rationality is the responsiveness to reasons of all kinds, including practical and testimonial reasons, the trust tradition follows. The disagreement about faith is a window into the disagreement about the nature of reason itself, and the debate is unresolved because the disagreement about reason is unresolved.

Sources

• Stanford Encyclopedia of Philosophy, "Religious Epistemology" — https://plato.stanford.edu/entries/religious-epistemology/
• Stanford Encyclopedia of Philosophy, "Blaise Pascal" — https://plato.stanford.edu/entries/pascal/
• Stanford Encyclopedia of Philosophy, "Thomas Aquinas" — https://plato.stanford.edu/entries/aquinas/
• Stanford Encyclopedia of Philosophy, "Alvin Plantinga" — https://plato.stanford.edu/entries/plantinga/

Related Topics

• What Is Reformed Epistemology? — the properly basic belief view.
• What Is Religious Experience? — the experiential evidence.
• What Is Agnosticism? — the situation the Wager presupposes.
• Who Bears the Burden of Proof for God? — the procedural question.
• Does God Exist? — the central question.
• Philosophy of Faith — the wider domain.