What is the difference between "rational" and "epistemically justified" in philosophy of religion, and why does Plantinga care about this distinction?

This distinction between "rational" and "epistemically justified" is one of Alvin Plantinga's most important contributions to contemporary religious epistemology. The distinction is subtle but decisive, as it radically changes how we evaluate religious beliefs epistemically. Understanding this difference is necessary for grasping Plantinga's epistemological project and his critique of classical evidentialism.

Inadequate Responses to Avoid

From some defenders of faith:

"The terms are synonymous; distinguishing between them is useless philosophical complexity." This is a conceptual error. The distinction has decisive implications for how we defend the rationality of faith. Conflating the concepts leads to falling into the trap of classical evidentialism that demands evidence and arguments for every belief, while Plantinga wants to transcend this requirement entirely.

"Plantinga says faith doesn't need justification." This is a misreading. Plantinga doesn't deny the importance of justification, but rather distinguishes between two types of epistemic evaluation. A belief may be perfectly rational without being justified in the classical evidentialist sense. This doesn't mean justification isn't important, but that rationality isn't reducible to it.

From some naturalist critics:

"The distinction is just a verbal trick to avoid the requirement for evidence." This is a superficial accusation. The distinction is grounded in deep epistemological analysis of the nature of knowledge and justification. Plantinga isn't avoiding the requirement for rationality, but redefining what it means for a belief to be rational in the first place.

"If faith is rational without justification, then any belief can be rational." This is a slippery slope fallacy. Plantinga doesn't say that every unjustified belief is rational, but rather sets precise conditions for when a belief is rational without inferential justification: that it results from cognitive faculties functioning properly in an appropriate environment and aimed at truth.

Why These Responses Are Inadequate

The common problem in these responses is failing to understand the deeper epistemological context of the distinction. Plantinga operates within a broader epistemological revolution in the twentieth century, challenging the classical foundationalist and evidentialist model of knowledge. The distinction between rational and justified is part of this larger project.

The Basic Distinction

Epistemically Justified: A belief is justified if the person has reasons, evidence, or arguments supporting it, and can access these reasons and present them when asked. This concept is internalist—it relates to what a person can access from within their epistemic consciousness.

Example: My belief that "2+2=4" is justified because I can provide the mathematical proof. My belief that "the sun will rise tomorrow" is justified because I can point to regularity in nature and physical laws.

Rational: A belief is rational if it results from cognitive faculties functioning properly in an environment suitable for these faculties, and they are aimed at producing true beliefs. This concept is externalist—it doesn't require the person to be conscious of the process that produced the belief.

Example: A child's belief that "my mother loves me" may be perfectly rational (resulting from properly functioning cognitive faculties that detect genuine love) without being justified (the child cannot provide philosophical arguments about the nature of love).

Why Plantinga Cares About This Distinction

The central reason: critiquing classical evidentialism, which says religious belief is rational only if supported by sufficient evidence and arguments. This critique has three dimensions:

First: The problem of application to basic beliefs. Many of our basic beliefs (such as the existence of the external world, the reliability of memory, the existence of other minds) cannot be justified by non-circular evidence, yet we consider them perfectly rational. If evidentialism were correct, these basic beliefs would be irrational—which is absurd.

Second: Basically produced beliefs. Some beliefs are produced directly by our cognitive faculties without conscious inference. My seeing a tree produces the belief "there is a tree" without need for inference. This belief is rational (resulting from the faculty of sight functioning properly) even if it's not inferentially justified.

Third: The sensus divinitatis. Plantinga suggests—following Calvin—that humans may possess a cognitive faculty that produces beliefs about God in a basic way (just as the faculty of sight produces beliefs about trees). If this faculty exists and functions properly, belief in God's existence is rational even without philosophical arguments.

Application to Religious Faith

According to Plantinga's distinction, religious belief can be:

1. Rational without being inferentially justified: If it results from the sensus divinitatis functioning properly, like the belief of a simple believer who feels God's presence in prayer without knowing philosophical arguments.

2. Both rational and justified: If supported by strong philosophical arguments, like the belief of a believing philosopher who has studied cosmological and teleological arguments.

3. Irrational even if apparently justified: If it results from malfunctioning faculties, like the belief of someone with paranoid delusions who believes he's a prophet and provides complex "evidence."

Significance for Contemporary Discussion

This distinction changed the trajectory of discussion in philosophy of religion:

From believers' side: It's no longer necessary to prove God's existence through philosophical arguments to establish the rationality of faith. It's sufficient that faith results from properly functioning cognitive faculties. This liberates simple faith from the charge of irrationality.

From critics' side: The discussion shifted from "Is there sufficient evidence?" to "Do the alleged religious cognitive faculties exist and are they reliable?" This is an entirely different discussion requiring new critical tools.

Critique of the Distinction

The distinction has faced criticism from multiple quarters:

From evidentialists: The distinction opens the door to accepting bizarre beliefs as rational. How do we distinguish between a genuine "divine sense" and psychological delusions?

From internalist epistemologists: Abandoning the requirement for conscious access to reasons makes rationality a vague and unverifiable concept.

From naturalists: The idea of "truth-aimed faculties" presupposes teleological design, which begs the question in the discussion of God's existence.

Where We Stand Today

The distinction between rational and justified has become widely accepted in contemporary epistemology, even outside philosophy of religion. But its application to religious beliefs remains controversial. Today's discussion revolves around: Are religious beliefs like basic perceptual beliefs? Or are they a special type requiring special criteria?

For god-database's method of cumulative rational preponderance (rajḥān ʿaqlī), this distinction is useful: it allows evaluating religious beliefs from multiple angles (basic rationality + inferential justification) without reducing one to the other.

For Advanced Reading

─ Advanced level: Critique of Proper Function and the design environment problem
─ Advanced level: The internalism/externalism debate in epistemic justification
─ "Reformed Epistemology" page on the website
─ Plantinga, "Reason and Belief in God" (1983)
─ Plantinga, Warrant: The Current Debate (1993)
─ BonJour, "Externalism/Internalism" in Companion to Epistemology (1992)