Concept

Methodological Naturalism

Intro

A lot of the most heated arguments between Christians and atheists turn on a confusion that almost nobody fixes. There are two completely different things called naturalism. Once you separate them, a lot of the "science has disproved God" talk falls apart.

The first one is methodological naturalism. It is a rule for doing science. When you are running an experiment or building a theory, restrict your explanations to natural causes, things you can measure, model, repeat, test. Do not invoke God or angels mid-experiment, because the experimental method cannot handle them. This rule is sensible and works. Newton followed it. Boyle followed it. So did Faraday, Maxwell, Mendel, Lemaître, and the Catholic priest-astronomer who invented Big Bang cosmology. None of them were atheists. The method does not require disbelief; it just brackets the question.

The second one is metaphysical naturalism. It is not a rule for doing science. It is a worldview claim about reality. It says, "only natural things exist; there is no God, no spirit, no supernatural reality at all." That is a philosophical position, not a scientific finding. Carl Sagan was famous for it. So is Richard Dawkins.

The slide between the two is where the trouble starts. Atheist popularizers will point to a scientific success, "we explained lightning, we explained disease, we explained the cosmos", and conclude that the supernatural is therefore proven nonexistent. But the explanations only counted as science because methodological naturalism was the rule of the game. Pointing to results obtained under that rule does not prove the rule's deeper cousin. The two are different propositions; the second does not follow from the first.

This matters in apologetics because the move "science has shown God doesn't exist" is almost always the slide between MN and MeN done quickly. Christian scientists have always been able to use the scientific method without contradicting their faith. The method is a tool, like a microscope. The microscope does not see God; that does not prove God does not exist.

The page below walks the history of the distinction, the major scholarly defenders (Plantinga, Ratzsch, McMullin), the application to debates over Intelligent Design, and the careful way Christians can affirm science wholeheartedly without smuggling in a worldview that goes beyond it.

In full

The methodological assumption, adopted by working scientists across most disciplines since the late 19th c., that scientific explanation should appeal only to natural causes (entities, forces, processes describable in terms of matter / energy / physical laws), explicitly excluding supernatural / divine / non-physical causes from consideration. Methodological naturalism (MN) is to be carefully distinguished from metaphysical naturalism (MeN; the worldview claim that only natural entities exist). MN is a working methodological assumption; MeN is a substantive philosophical commitment. The conflation of MN with MeN is one of the most consequential confusions in contemporary religion-and-science debates: atheist polemicists frequently treat scientific findings (which presuppose MN as a working method) as evidence for MeN (the philosophical claim that nothing supernatural exists). The harmony tradition refuses this conflation and engages MN as a legitimate-but-limited working assumption that does not entail metaphysical-naturalist conclusions.

The MN / MeN distinction

The two senses of "naturalism" are easily conflated in popular discourse but are philosophically distinct:

Term	Type	Claim
Methodological Naturalism (MN)	methodological assumption	In doing scientific investigation, restrict explanatory appeal to natural causes. No claim about whether supernatural causes exist; only a methodological exclusion from the explanatory toolkit during scientific work.
Metaphysical Naturalism (MeN)	substantive worldview claim	Only natural entities exist. No supernatural beings, no transcendent realities, no non-physical existents. A philosophical position about the totality of what is.

The crucial distinction:

MN is a method, not a metaphysics. A theist scientist can practice MN consistently (restricting explanatory appeal to natural causes during scientific investigation) without committing to MeN (without claiming supernatural causes don't exist). Many of the founding modern scientists (Newton, Boyle, Faraday, Maxwell, Mendel, Lemaître) practiced MN while affirming theism.
MeN is a worldview, not a method. Affirming MeN does not entail any particular methodology; one could in principle endorse MeN philosophically while practicing different methods (though in practice MeN-adherents typically support MN).
MN does not entail MeN. This is the central apologetic point: the success of MN-as-method does not rationally compel MeN-as-worldview. Scientific success-via-MN is compatible with theism; MeN is an additional philosophical commitment not provided by the scientific findings themselves.

Historical development

Pre-modern: no MN/MeN distinction

In the pre-modern period (Aristotle through the medieval scholastics + early modern science), the working assumption was that scientific investigation could legitimately appeal to both natural causes and ultimate causes including divine ones. Aquinas's Five Ways (ST I q.2 a.3) move from natural-observation to divine cause without methodological restriction. Newton's Principia (1687) explicitly invokes God as the ground of absolute space + time + the lawlike order of nature.

19th-c. emergence of MN

MN as a methodological commitment emerged in the late 19th c. as scientific specialization deepened:

Charles Darwin (On the Origin of Species 1859), explanatorily restricted to natural causes (variation + selection) without invoking divine action; this was operational MN even though Darwin himself remained ambiguous about MeN.
Thomas Henry Huxley ("Darwin's bulldog"), explicitly defended MN as the working method of biology while himself affirming agnosticism (a position he coined for his own MN+MeN-uncertainty stance).
John Tyndall, Belfast Address (1874), programmatic statement of MN as the method of scientific investigation.
Andrew Dickson White, A History of the Warfare of Science with Theology (1896), popularized the "warfare-thesis" framing of religion-vs-science, often conflating MN with MeN.

By the early 20th c., MN was the default working assumption across mainstream natural-science disciplines.

20th-c. philosophical articulation

The MN/MeN distinction was sharpened in 20th-c. philosophy of science:

Logical Positivism (Vienna Circle), sought to reduce science to verificationism; methodological naturalism was assumed but not always sharply distinguished from metaphysical naturalism.
Karl Popper, falsificationism: science investigates falsifiable claims about the natural world; supernatural claims are typically non-falsifiable and thus outside science's scope. This is MN-with-clear-boundary, not MeN.
Robert Pennock, popularized MN/MeN distinction in the 1990s in defense of teaching evolution + excluding intelligent-design from public-school science classrooms.

21st-c. ID debate and the MN question

The Intelligent Design (ID) movement (Behe + Dembski + Meyer + Plantinga) explicitly challenges MN as a methodological commitment, arguing:

MN is not actually epistemically required.
ID inferences (specified-complexity → mind) are valid scientific inferences.
The MN restriction is a sociological convention, not a methodological necessity.

Mainstream science responds:

MN is supported by long track record of explanatory success.
ID inferences have not produced testable predictions.
The MN convention preserves science from non-falsifiable speculation.

The MN-as-methodology-only debate continues; the MN/MeN distinction is the central conceptual frame.

Why MN does not entail MeN, key arguments

1. Methodological assumption ≠ metaphysical commitment

The argument is parallel to: "I drive on the right side of the road in the US" does not entail "right-side-driving is metaphysically required", it is a methodological convention with practical justification. Similarly, MN is a methodological convention with practical justification (restricting investigation to repeatable, testable, falsifiable claims) and does not entail the metaphysical claim that nothing else exists.

2. Scope of MN is restricted

MN applies within scientific investigation, not across all rational inquiry. Mathematics, logic, history, philosophy, theology, ethics, these disciplines do not adopt MN, and rightly do not (the methods that work for chemistry don't work for proving mathematical theorems). MN is the method of natural science, not of all knowledge.

3. Historical scientists practiced MN as theists

Newton, Boyle, Faraday, Maxwell, Mendel, Lemaître, Polkinghorne, Collins (Francis), Lennox, McGrath, Numbers, many founding-and-leading scientists across centuries practiced MN scrupulously while affirming theism. The compatibility is empirical-historical, not just theoretical.

4. MeN is itself not scientifically demonstrable

MeN is a philosophical claim: "only natural entities exist." This claim cannot be tested by science using MN (since MN restricts to natural-causal explanation; MN cannot adjudicate the existence of non-natural entities). MeN is therefore a philosophical extension of MN, not a scientific finding. Endorsing MN does not commit one to MeN; the leap to MeN requires philosophical argument, not just scientific success.

5. Plantinga's evolutionary argument against naturalism (EAAN)

Alvin Plantinga's Warranted Christian Belief (2000) and Where the Conflict Really Lies (2011) press a sharper point: MeN combined with evolutionary theory generates a self-undermining situation. If both MeN and evolutionary theory are true, our cognitive faculties were selected for survival, not truth; therefore we have no reason to trust our cognitive faculties' deliverances, including the deliverance "MeN is true." MeN is therefore self-undermining if combined with naturalistic evolutionary epistemology. See Argument from Reason for the full development.

Apologetic deployment

1. Against the "science has shown MeN is true" inference

The inference MN works → MeN is true is the central apologetic confusion to expose. Walk the interlocutor through:

What does MN claim? (methodological exclusion)
What does MeN claim? (metaphysical exhaustion)
Are these the same thing? (no, one is a method, one is a worldview)
Does MN's success imply MeN? (no, MN restricts what science investigates; it doesn't pronounce on what exists outside science's scope)

2. Against the "God of the gaps" objection

The atheist objection (God of the Gaps, concept hub pending) charges Christians with invoking God only to fill gaps in natural-causal explanation, with the gaps progressively closed by ongoing scientific advance.

The MN/MeN distinction strengthens the response:

The Christian theological tradition does not invoke God as a gap-filler but as the ground of natural-causal order. Newton invoked divine action not to fill a mechanism-gap but to ground absolute space-time.
The MN restriction means science cannot adjudicate divine grounding claims; God-as-ground operates outside MN's scope.
"God of the gaps" critiques apply specifically to poor theology (gap-fillers); they do not apply to classical theism (ground-of-order). See Aseity + Privation + Eternity (Divine).

3. Engaging Intelligent Design controversies

ID's challenge to MN is methodological (does science require MN?) and is the central debate in philosophy of biology.

The Christian-apologetic position need not commit to ID's challenge being correct; it can affirm:

MN is a successful working method for most of natural science.
MeN is not entailed by MN's success.
The question of whether ID inferences are scientific is independent of the question of whether design exists in nature; theism can affirm design-in-nature without claiming science-must-detect-it.

Plantinga's Where the Conflict Really Lies (2011) develops a sophisticated middle position: MN is appropriate within science as currently practiced, but MN does not exhaust rational inquiry, and the deeper metaphysical questions (does mind underlie the universe? is the universe designed?) remain rationally open.

4. Against the "religion vs. science" warfare narrative

Stephen Jay Gould's "non-overlapping magisteria" (NOMA) is a partial response, religion and science occupy non-overlapping domains. Christian apologists generally accept the NOMA-domain insight but reject the strict-non-overlap claim (Christian theology has implications for what science investigates, e.g., the universe being intelligible at all, the regularity of natural law, the existence of objective truth-conditions for scientific claims).

The MN/MeN distinction sharpens the response: science (under MN) and theology (under its own methods) operate with different scopes; they conflict only when (a) bad theology overreaches into science's MN-domain, or (b) bad MeN-philosophy overreaches into theology's domain. Properly bounded, MN-science and Christian theology are compatible.

5. The "God hypothesis" question (Hawking, Dawkins)

Stephen Hawking (The Grand Design 2010) and Richard Dawkins (The God Delusion 2006) argue the "God hypothesis" is dispensable given current physics. The MN/MeN distinction reframes:

Hawking's argument operates within MN, physics needs no supernatural-causal-input.
The argument does not establish MeN, it does not show that no supernatural beings exist; only that physics-restricted-to-natural-causes-can-do-physics.
The leap from "physics succeeds without invoking God" to "therefore no God" is precisely the MN→MeN conflation.

Connection to Scripture

The MN/MeN distinction does not have direct biblical anchors (it's a philosophy-of-science distinction), but the broader theological context:

Genesis 1:1, creation ex nihilo is the foundation; God-as-creator-of-the-natural-order is the ultimate ground of MN's success (the natural order has the lawlike regularity that makes MN possible).
Romans 1:18-21, natural-revelation evidentialism: God's invisible attributes are clearly seen through what is made, natural revelation operates within nature, suggesting that the natural-causal order itself bears witness to God.
Proverbs 25:2, "It is the glory of God to conceal a matter, but the glory of kings is to search out a matter." Natural investigation (MN) is itself a divinely-blessed activity; the Christian tradition has affirmed scientific inquiry as obedience to this pattern.
Acts 17:28, "for in Him we live and move and exist", Pauline articulation of God as the ground of natural existence; ground-of-order theology rather than gap-filler theology.

Patristic / scholarly note

Robert T. Pennock, Tower of Babel: The Evidence Against the New Creationism (MIT Press, 1999), popularized the MN/MeN distinction in defense of mainstream evolutionary biology against ID + creationism.
Alvin Plantinga, Where the Conflict Really Lies: Science, Religion, and Naturalism (Oxford UP, 2011), comprehensive Christian-philosophical engagement; argues there is "superficial conflict but deep concord" between science and theistic religion, while there is "superficial concord but deep conflict" between science and metaphysical naturalism.
Alvin Plantinga, Warranted Christian Belief (Oxford UP, 2000), develops the EAAN (evolutionary argument against naturalism), MeN + evolutionary epistemology generates self-undermining.
John Lennox, God's Undertaker: Has Science Buried God? (Lion Hudson, 2007/2009), popular-level treatment from an Oxford mathematician; develops the science-and-theism harmony thesis.
Stephen C. Meyer, Return of the God Hypothesis (HarperOne, 2021), ID-perspective argument that evidence from fundamental physics + cosmology + biology supports theism over MeN; directly engages the MN-restriction debate.
Ronald Numbers (ed.), Galileo Goes to Jail and Other Myths about Science and Religion (Harvard UP, 2009), comprehensive history-of-science treatment refuting the warfare-thesis narrative.
John Polkinghorne, Belief in God in an Age of Science (Yale UP, 1998), Christian-physicist articulation of compatibility.
Francis Collins, The Language of God (Free Press, 2006), head of Human Genome Project + NIH; Christian-scientist articulation of theistic-evolution compatibility.