Reformed Epistemology

Reformed epistemology is the most influential development in twentieth-century religious epistemology: the thesis that belief in God can be rational, justified, and warranted without being based on arguments or evidence — that it can be properly basic, accepted in the basic way (not inferred from other beliefs) and yet entirely in order. Developed by Alvin Plantinga, Nicholas Wolterstorff, and William Alston (drawing on the Reformed theological tradition of Calvin, hence the name), it directly rejects the evidentialist objection: the demand for evidence is not a neutral canon of rationality but a contestable — and ultimately self-defeating — epistemological assumption. If correct, it removes the requirement that natural theology succeed for faith to be reasonable, and shifts the entire faith-and-reason debate.

This page sets out proper basicality and the sensus divinitatis, Plantinga's "warrant" theory and the de jure / de facto distinction, and the principal objections — above all the Great Pumpkin over-permissiveness worry.

Proper basicality

Classical foundationalism divides justified beliefs into basic (foundational, not held on the basis of other beliefs) and non-basic (inferred from basic ones). It then restricts properly basic beliefs to a narrow class — typically the self-evident (that $2 + 2 = 4$ ), the incorrigible (that I am in pain), and the evident to the senses (that I see a tree). On this classical picture, belief in God is not in any of these classes, so it must be non-basic — held, if at all, on the basis of evidence (the arguments). That is the engine of the evidentialist objection.

Reformed epistemology attacks the criterion of proper basicality, not the foundationalist structure. Plantinga's two-part argument:

The classical criterion is self-referentially incoherent. The criterion "a belief is properly basic only if self-evident, incorrigible, or evident to the senses" is itself none of these — it is not self-evident, not incorrigible, not evident to the senses — and there is no argument for it from such beliefs. So by its own standard, the criterion is not rationally believable. Classical foundationalism thus fails on its own terms.
The criterion is too narrow. Applied consistently it would condemn vast ranges of obviously rational belief that are not self-evident, incorrigible, or sensory and not inferred from such: memory beliefs ("I had breakfast"), beliefs in other minds, beliefs in the reality of the past and the external world, inductive beliefs. We accept all these in the basic way, without argument, and we are right to. So the class of properly basic beliefs is much wider than the classical criterion allows.

Once the gate is open, the question is whether theistic belief belongs among the properly basic. Plantinga argues it does — not belief in the bare proposition "God exists," but the rich, particular beliefs that arise in concrete circumstances: God is speaking to me, God forgives me, God created all this, God disapproves of what I have done. These arise non-inferentially, in response to experience (the beauty of nature, the sense of guilt, the reading of scripture), much as perceptual beliefs arise in response to sensory experience — grounded in the circumstance though not inferred from a premise.

The sensus divinitatis

The positive account of why such beliefs are warranted invokes a faculty. Following Calvin (and Aquinas's cognitio Dei naturalis), Plantinga posits a sensus divinitatis — an innate "sense of the divine," a cognitive faculty or disposition that, triggered in appropriate circumstances (awe at the heavens, moral experience, danger, gratitude), produces belief in God directly. On this model:

Theistic belief is the natural output of a belief-forming faculty, parallel to perception, memory, and a priori intuition.
When the faculty functions properly (is not damaged or suppressed), in the right environment, the beliefs it yields are warranted — whether or not the believer can produce an argument, exactly as perceptual beliefs are warranted by properly functioning perception, not by an argument for perception's reliability.
The widespread human tendency to religious belief (the data the common-consent argument cites) is what one would expect if such a faculty exists; and the sin-induced malfunction or suppression of it explains, on the theological story, why some do not believe (connecting to the hiddenness debate's premise-4 dispute).

Warrant and the de jure / de facto distinction

In his Warrant trilogy (culminating in Warranted Christian Belief, 2000), Plantinga gives the externalist machinery. Warrant — what converts true belief into knowledge — is, on his account, the property a belief has when it is produced by cognitive faculties that are (i) functioning properly, (ii) in a congenial environment, (iii) according to a design plan (iv) successfully aimed at truth. This is a thoroughly externalist account: warrant depends on facts about the origin and reliability of the belief, not on the believer's reflective access to evidence.

The payoff is the de jure / de facto distinction and Plantinga's central claim:

A de facto objection to theism argues that it is false (e.g. the problem of evil as a disproof).
A de jure objection argues that, whatever its truth-value, theistic belief is irrational, unjustified, or unwarranted (the evidentialist objection; Freudian/Marxist debunking).

Plantinga's thesis: there is no viable de jure objection independent of the de facto question. For if God exists and has created us with a sensus divinitatis to know him, then theistic belief is produced by a properly functioning, truth-aimed faculty and is warranted (indeed is knowledge). So theistic belief is warranted if true — the only way to show it unwarranted is to show it false. Hence the atheologian cannot retreat to "belief in God is irrational even if there happens to be a God"; the de jure complaint collapses into the de facto one, and the real question is just whether God exists. This neatly reverses the evidentialist framing: the burden is not on the theist to produce evidence, but on the atheist to disprove God in order to convict belief of irrationality.

Objections

The Great Pumpkin objection. The central worry (raised by Plantinga himself): if theism is properly basic without evidence, why not anything — voodoo, astrology, belief in the Great Pumpkin? Plantinga's reply: proper basicality is not arbitrary license; a belief is properly basic only if produced by a properly functioning, truth-aimed faculty. Theism (if true) is so produced; Great-Pumpkinism is not (there is no Great-Pumpkin-sense). The criterion is met by examples and by the proper-function theory, not by fiat. Critics object that this answer is available to anyone: the voodoo practitioner can equally claim a reliable voodoo-faculty, so the dispute just relocates to which faculties are genuine — which cannot be settled without settling the de facto questions.
Circularity. The warrant of theistic belief is certified by the reliability of the sensus divinitatis, whose existence and reliability are guaranteed only if theism is true. So the account uses theism to vindicate theistic belief. Plantinga grants the circularity but argues it is not vicious — it is the same epistemic circularity that afflicts every attempt to validate a basic source (one cannot establish the reliability of perception, memory, or reason without using perception, memory, or reason). No belief-source can be non-circularly validated; theism is no worse off.
The "son of Great Pumpkin" / parity with rival religions. Even granting proper function, which religion's basic beliefs are warranted? A Muslim, Hindu, or Mormon can run the identical argument for their basic religious beliefs. Reformed epistemology seems to confer warrant on mutually incompatible faiths, which connects to the problem of religious diversity and disagreement — and to the worry that defensive parity (no one can be convicted of irrationality) comes at the price of offensive impotence (the argument persuades no one not already inside).
The defeater problem. Even a properly basic belief can be defeated by counter-evidence. The problem of evil, divine hiddenness, and the debunking explanations are pressed as defeaters that, even if theism starts out properly basic, undercut its warrant — so Reformed epistemology does not exempt the theist from engaging the atheological case after all (Plantinga concedes this, devoting much of Warranted Christian Belief to defeating the defeaters).

Where Reformed epistemology sits

Reformed epistemology is the externalist answer to the evidentialist objection: belief in God can be properly basic and warranted — even knowledge — when produced by a properly functioning, God-given sensus divinitatis, no argument required, just as perception yields knowledge without an argument for its reliability. Its signal achievement is the de jure / de facto result: there is no way to convict theistic belief of irrationality without first showing it false, which dissolves the "even if there's a God, belief is irrational" complaint and reframes the burden of proof. Its signal liability is the Great Pumpkin family of worries — that the same form licenses any faith, so the view is defensively strong (no believer can be shown irrational) but offensively weak (it gives the unbeliever no reason to convert) and inherits the full force of religious diversity and of defeaters like evil and hiddenness. It is best understood not as an argument for God but as a defense of the rationality of belief, the natural ally of the argument from religious experience (which makes a parallel move with a perceptual analogy) and the deepest reply available in the faith-and-reason debate to the charge that faith without proof is irrational.