Does Plantinga's "Evolutionary Argument Against Naturalism" (EAAN) succeed when applied specifically to moral knowledge, or does it collapse before objections particular to this domain?

This question raises a specialized application of one of the most famous contemporary arguments in philosophy of religion. Alvin Plantinga, in "Warrant and Proper Function" (1993) and "Where the Conflict Really Lies" (2011), developed a powerful argument against naturalism. The question is: does the argument succeed when specialized to moral knowledge?

Inadequate Responses to Be Avoided

From some defenders of the argument:

"Plantinga's argument succeeds in all domains with equal force." Hasty generalization. Moral knowledge has distinctive epistemic properties that may affect the argument. Each epistemic domain requires special analysis.

"Ethics proves God, so the argument succeeds automatically." Clear circularity. We cannot assume what we are trying to prove. The argument must stand on its own, not depend on its conclusion.

"Evolution doesn't explain ethics, so the argument is correct." Logical leap. Even if evolution fails to fully explain ethics, this doesn't automatically mean EAAN succeeds. One must prove that naturalism + evolution undermines the reliability of our specifically moral beliefs.

From some critics:

"Evolutionary ethics explains everything, so the argument fails." Exaggerated claim. Evolutionary ethics explains some aspects (cooperation, kin altruism), but faces challenges in explaining other aspects (universal duties, rights of strangers, radical sacrifice).

"Moral knowledge is subjective, so the argument doesn't apply." Meta-ethical error. Even if some moral judgments are culturally relative, this doesn't negate the existence of objective moral facts (like the wrongness of unprovoked torture). The argument targets the reliability of our beliefs about these facts.

"The argument is religion in disguise, so it should be rejected." Methodological error. The argument is philosophical in structure, starting from premises the naturalist accepts. That it leads to conclusions supporting theism doesn't invalidate it.

Why These Responses Are Inadequate

They avoid technical engagement with the details of the argument when applied specifically to moral knowledge. Moral knowledge has unique epistemic characteristics that affect how the argument works.

Structure of Plantinga's Original Argument (EAAN)

The argument states: If philosophical naturalism and Darwinian evolution are both true, then the probability that our cognitive faculties are reliable is very low. Why?

1. Evolution selects for adaptive behavior, not true beliefs. What matters for survival is successful behavior, regardless of the truth of the beliefs that cause it.

2. Belief content is invisible to natural selection. Many false beliefs can produce adaptive behavior. Plantinga's example: a creature could believe tigers are "kind gods who want to befriend him in the afterlife," flee from them, and survive.

3. Therefore: P(R|N&E) is low. The probability of our faculties' reliability (R) given naturalism (N) and evolution (E) is low.

4. One who accepts N&E must doubt the reliability of his faculties. This includes his faculty for evaluating N&E itself.

5. Therefore: N&E defeats itself. Evolutionary naturalism undermines its own epistemic foundation.

Applying EAAN to Moral Knowledge

When specializing the argument to moral knowledge, new considerations emerge:

First Strength: The disconnect between adaptation and moral truth is clearer.

In empirical knowledge, one might say: "knowing where food and predators are is adaptive, and truth helps adaptation, so evolution indirectly selects for truth." But in ethics, the disconnect is clearer:

─ What helps survival and reproduction isn't necessarily morally correct.
─ Many adaptive behaviors (aggression toward strangers, genetic selfishness, discrimination against the different) seem morally wrong.
─ Many noble moral beliefs (universal human rights, duty to help distant strangers) are clearly non-adaptive.

This strengthens EAAN: if evolution selects for moral beliefs that aid survival regardless of their truth, the reliability of our moral intuitions is strongly suspect.

Second Strength: "Debunking Explanations" are stronger.

Sharon Street in "A Darwinian Dilemma for Realist Theories of Value" (2006) developed a parallel argument: if our moral beliefs are the product of evolutionary pressures, and these pressures have no relation to independent moral facts, this "debunks" the reliability of these beliefs.

Example: we tend to favor our relatives. Evolutionary explanation: genes that make their carriers help relatives (who share genes with them) spread more. This explanation points to no moral fact about "the duty to favor relatives." So the tendency's reliability is suspect.

This supports EAAN applied to ethics: evolution gives us moral inclinations for reasons unrelated to moral truth.

First Challenge: Ethics may be adaptive in indirect ways.

The critic might say: correct ethics helps cooperation, and cooperation is adaptive. So evolution might select for correct ethics.

Problems with this response:

─ It explains only ingroup cooperation ethics, not universal duties.
─ Cooperation can be achieved with "ethical" rules that are wrong (tribal racism, for instance).
─ Much correct ethics (justice toward enemies) is non-adaptive.

The response faces a dilemma: either reduce ethics to "what helps cooperation" (losing ethics' meaning), or acknowledge independent moral facts (returning us to the problem).

Second Challenge: Moral knowledge may be constructive, not evolutionary.

The critic might say: yes, evolution gave us initial tendencies, but we build on them with reason. Mature moral knowledge is the product of critical thinking, not instinct.

Problems with this response:

─ Reason itself is a product of evolution. If EAAN succeeds, it also questions reason's reliability.
─ Rational construction starts from initial intuitions. If these are unreliable, the entire construction is threatened.
─ History shows "reason" has justified many atrocities. Reason alone, without a reliable foundation, is insufficient.

Third Challenge: Conceptual necessity of moral reliability.

David Enoch in "The Epistemological Challenge to Metanormative Realism" (2010) argues: we cannot abandon trust in some basic moral judgments (like the wrongness of unprovoked torture). This is a conceptual necessity for practical agency.

Plantinga's likely response: this confirms the problem rather than solving it. If we are "compelled" to trust moral intuitions without a reliable basis, this deepens the naturalist's epistemic predicament.

Fourth Challenge: "Wholesale" rather than "retail" explanation.

Some naturalists propose: we don't need an evolutionary explanation for every moral judgment. It suffices to explain the general capacity for moral thinking. This capacity may be adaptive, even if it produces non-adaptive judgments.

Problems with this response:

─ It explains the capacity's existence, not its reliability. A capacity that evolved for adaptive purposes may be unreliable for reaching truths.
─ It's like saying: "evolution gave us imagination, and imagination produced mathematics." This doesn't explain why mathematics is correct.
─ The capacity for "moral thinking" may just be the capacity to rationalize evolutionary interests in moral language.

Fifth Challenge: Ethics as "response-dependent facts."

Some philosophers (like David Lewis in his later works) propose: moral facts aren't completely independent of our responses. Right and wrong are partially defined by what we respond to in certain ways under ideal conditions.

Plantinga's likely response: this either collapses into subjectivism (making moral facts depend on our responses) or requires explaining why ideal responses track mind-independent moral reality. The naturalist still needs to explain this tracking without invoking design.

Where We Stand in This Debate Today

The period 2020-2026 saw notable developments at this intersection of EAAN and moral knowledge. On one hand, philosophers like Justin Clarke-Doane in "Morality and Mathematics" (2020) continued deepening the challenge, showing that evolutionary debunking arguments affect both mathematics and ethics, thus expanding EAAN's scope. On the other hand, naturalists like Richard Joyce and Erik Wielenberg developed more sophisticated responses: Joyce by adopting moral error theory that avoids the problem by denying moral facts altogether, and Wielenberg by attempting to build naturalistic moral realism through connecting moral facts to natural facts via necessary supervenience relations. However, recent debate revealed that both responses face structural difficulties: the first abandons moral knowledge rather than rescuing it, and the second needs to explain why moral facts necessarily follow natural facts without deeper metaphysical foundation. The debate remains open and increasingly intense.

From the Perspective of Rational Preponderance (rajḥān ʿaqlī)

This site's methodology addresses this question within cumulative rational preponderance, not decisive proof in one direction:

─ EAAN applied to moral knowledge constitutes a real consideration against naturalism, not a decisive proof. The disconnect between adaptation and moral truth is clearer than in empirical knowledge, giving the argument additional force in this domain.
─ The specialized objections (rational construction, response-dependent facts, wholesale explanation) partially weaken the argument but don't invalidate it, as they all face structural problems we outlined above.
─ This consideration adds to other considerations (the independent moral argument, fine-tuning, consciousness) in building cumulative preponderance that makes theistic explanation of moral knowledge rationally more probable than naturalistic explanation, while acknowledging that the naturalist possesses theoretical resources not yet fully exhausted.