Concept

Naturalism

Intro

Naturalism is the philosophical view that nature is all there is. There is no God above nature, no soul standing outside the body, no angels or demons, no afterlife, no miracles. Whatever exists is part of the spatiotemporal causal order that the natural sciences investigate. Anything that does not fit there is mistake, myth, or projection.

This view comes in two very different forms, and the difference matters. Methodological naturalism is a working rule for science: when doing physics or biology, look for natural causes and bracket the supernatural for the duration of the inquiry. Many Christian scientists work this way without controversy. Metaphysical naturalism is a worldview: it claims natural causes are the only causes that exist anywhere, full stop. The first is a tool. The second is a substantive philosophical commitment that has to be argued for, not assumed.

Naturalism became the default worldview of secular Western academia in the twentieth century, largely through W. V. O. Quine, the Vienna Circle, and the broader scientistic turn. Most contemporary objections to Christian faith are downstream of it. If naturalism is the air everyone is taught to breathe, then arguments for God, the soul, free will, objective morality, and the reliability of reason all have to push against a perceived default. The first task of Christian apologetics on this front is to show that it is not a default at all, but one substantive worldview among others, with its own evidential burdens.

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In full

Metaphysical naturalism is the ontological thesis that the natural order (variously specified as the physical, the spatiotemporal, or the scientifically tractable) exhausts what there is. There is no transcendent God, no immaterial soul, no non-natural normative facts, no Platonic abstracta on strong versions, no irreducibly mental properties on strict versions. The view is typically conjoined with a causal closure thesis (physical effects have only physical causes), a scientism-adjacent epistemology (natural science is the paradigm or sole source of substantive knowledge of reality), and a methodological commitment to inquiry that proceeds without appeal to the supernatural. The most influential contemporary defenses are David Papineau, Philosophical Naturalism (Blackwell 1993) and Thinking about Consciousness (Oxford 2002); W. V. O. Quine, Word and Object (MIT 1960) and "Epistemology Naturalized" (1969); and the essays collected in Mario De Caro and David Macarthur, eds., Naturalism in Question (Harvard 2004) and Naturalism and Normativity (Columbia 2010), which map both the orthodox program and the heterodox liberal-naturalist response.

Methodological vs metaphysical

The most important distinction in the entire naturalism debate. Conflating these two is the single most common move in contemporary religion-and-science argument, and the apologist who can keep them apart owns ground that most popular naturalists do not realize they have conceded.

Methodological naturalism (MN)

A working rule for scientific inquiry: bracket the supernatural during the investigation, look for natural causes, and require natural-cause explanations to count as scientific. MN is a procedural commitment about how science conducts itself, not a substantive claim about what exists. The classic articulation in philosophy of science is Ronald Numbers, "Science Without God: Natural Laws and Christian Beliefs" (in Lindberg and Numbers, eds., When Science and Christianity Meet, Chicago 2003), which traces MN's historical emergence as a Christian methodological self-restriction (Bacon, Boyle, the Royal Society) rather than as an atheist platform.

MN is compatible with theism. A Christian scientist can endorse MN as the appropriate discipline-internal method (do not invoke divine intervention as a scientific explanation for protein folding) while denying metaphysical naturalism altogether (God exists, sustains the natural order, and is the ultimate explanation of why the natural order behaves lawfully).

See Methodological Naturalism for the dedicated hub.

Metaphysical naturalism (MeN)

A worldview claim: nature is all there is, full stop. No God, no soul, no transcendent reality, no non-natural normative facts. This is a substantive ontological thesis on a par with theism or idealism, and it requires argument, not stipulation. It is not the default position from which other worldviews must depart; it is one position among others, and it has to compete on evidence and explanatory adequacy.

The conflation as a rhetorical move

Popular naturalists routinely slide from MN to MeN as if the two were the same view, or as if MN's success in the laboratory established MeN's truth as a worldview. The structure of the move:

• Premise 1: science assumes methodological naturalism.
• Premise 2: science has been spectacularly successful.
• Conclusion (illicit): therefore metaphysical naturalism is true (or at least the only intellectually respectable worldview).

The conclusion does not follow. MN's success establishes that bracketing the supernatural during scientific inquiry is a productive research strategy. It does not establish that no supernatural reality exists. The success of "search for your keys under the streetlight" as a search procedure does not establish that the keys are under the streetlight; it establishes that searching there is tractable. Treating MN's procedural success as MeN's metaphysical vindication is what philosophers of science call the streetlight fallacy applied to ontology.

This is the single most useful rhetorical correction in contemporary worldview debate.

Major variants

Metaphysical naturalism comes in stronger and weaker forms, and apologetic engagement should target the version actually being defended.

Strict reductive (physicalist) naturalism

The strongest version. Only the entities of fundamental physics ultimately exist. Chemistry reduces to physics, biology reduces to chemistry, psychology reduces to biology, and mental states reduce to (or are identical with) brain states. Folk-psychological categories are useful approximations or, on harder eliminativist versions, simply false.

Defenders: Patricia Churchland, Neurophilosophy (MIT 1986); Paul Churchland, Matter and Consciousness (MIT, 3rd ed. 2013); Daniel Dennett, Consciousness Explained (Little Brown 1991); Alex Rosenberg, The Atheist's Guide to Reality (Norton 2011), the bullet-biting version that openly accepts nihilism about meaning and morality as the cost.

Non-reductive (emergent) naturalism

Mental, biological, social, and normative properties are real but supervene on (or are realized in) physical states without being reducible to them. The mental cannot exist without the physical substrate but cannot be translated without remainder into physics-talk.

Defenders: Jaegwon Kim, Mind in a Physical World (MIT 1998), the classic statement and critique; John Searle, The Rediscovery of the Mind (MIT 1992) and Mind: A Brief Introduction (Oxford 2004), with his "biological naturalism." Kim is famous for arguing that non-reductive physicalism collapses into either reductive physicalism or dualism, the so-called causal exclusion problem.

Liberal naturalism

A broader naturalism, defended notably by Mark Bishop and the De Caro-Macarthur circle, that allows for non-reductive normative, mathematical, and even ethical reality without admitting the supernatural. The motivation: strict physicalism makes a hash of reasons, persons, values, and normativity; a liberal naturalism that takes these seriously as part of nature is more honest to lived human experience and to the structure of scientific reasoning itself.

Defenders: Mario De Caro and David Macarthur, eds., Naturalism in Question (Harvard 2004) and Naturalism and Normativity (Columbia 2010); John McDowell, Mind and World (Harvard 1994), with his "second nature" naturalism; Hilary Putnam, Ethics without Ontology (Harvard 2004), late-Putnam pragmatist naturalism.

The Christian critic should note: liberal naturalism is much closer to a kind of secular humanism than to strict physicalism, and many of its commitments (irreducible normativity, the reality of value, the genuineness of persons) are easier to ground theistically than naturalistically. Liberal naturalism is in some ways an unstable halfway house.

Quinean naturalism

A distinctive program inherited from W. V. O. Quine in Word and Object (1960), "Epistemology Naturalized" (1969), and Theories and Things (1981). Three commitments:

• Ontological naturalism: the ontological commitments of our best total theory of the world are the entities that theory must quantify over. Whatever ineliminably appears in our best science exists; whatever does not, does not.
• Methodological naturalism: there is no first philosophy. Epistemology is continuous with empirical science. Philosophy is not a separate discipline that adjudicates science from outside; it is part of the same web of belief.
• Holism: beliefs face the tribunal of experience only collectively, not individually. Revision can in principle reach anywhere, including logic.

Quinean naturalism is the dominant background commitment of late-twentieth-century analytic philosophy. It gives metaphysical naturalism its most disciplined philosophical formulation and ties it directly to the methodology of natural science.

Eliminative materialism

The hardest version: not only are mental states reducible to brain states, the folk-psychological categories (beliefs, desires, qualia) do not really refer to anything. They are like phlogiston and witches, useful pre-scientific stories that mature neuroscience will displace.

Defenders: Patricia Churchland, Paul Churchland. The position has the virtue of consistency and the vice of being apparently self-refuting: the eliminativist asserts that nobody really has beliefs, which is itself a belief.

Historical development

The naturalist tradition does not begin with the Vienna Circle. It has deep antecedents.

Ancient and early-modern anticipations

• Lucretius, De Rerum Natura (1st century BC). The Epicurean materialist cosmology: atoms swerving in the void, no providential gods, no afterlife. The literary fountainhead of Western naturalism.
• Baruch Spinoza, Ethics (1677). The pantheist identification of God with nature (Deus sive Natura) is not quite naturalism in the modern sense, but it removes the transcendence-of-nature gap and inaugurates the immanent-only framework that later naturalists radicalize.
• Pierre-Simon Laplace (early 19th century). Famously responding to Napoleon's question about God's role in his celestial mechanics: "Je n'avais pas besoin de cette hypothèse-là" (I had no need of that hypothesis). The Laplacean dream: a closed deterministic physical universe with no explanatory gap for theistic intervention.

The positivist line

• Auguste Comte, Cours de Philosophie Positive (1830-1842). The "law of three stages": theological, metaphysical, positive (scientific). Human knowledge inevitably progresses from explanation by gods, to explanation by abstract essences, to explanation by empirical laws. Religion belongs to the first stage and is superseded.
• Logical positivism / the Vienna Circle (1920s-1930s). Moritz Schlick, Rudolf Carnap, Otto Neurath, A. J. Ayer (Language, Truth and Logic, 1936). The verificationist program: meaningful statements are either analytic (true by definition) or empirically verifiable. Theological statements are neither, hence meaningless. Metaphysics is dissolved by logic, not refuted by science.

Logical positivism collapsed by the 1960s under its own internal critiques (the verificationist criterion fails its own test, the analytic/synthetic distinction comes under attack from Quine, and so on), but its anti-metaphysical spirit was absorbed into the subsequent naturalist program.

The Quinean turn

• W. V. O. Quine, "Two Dogmas of Empiricism" (Philosophical Review, 1951), Word and Object (1960), "Epistemology Naturalized" (1969). The seminal move: replace logical-positivist anti-metaphysics with a continuous, holistic, scientific-realist naturalism. Quine's program does not dismiss metaphysics; it absorbs metaphysics into science. Whatever our best science says exists, exists.

Contemporary academic naturalism

The dominant background commitment of post-1970 Anglophone philosophy. Key statements:

• Wilfrid Sellars, "Philosophy and the Scientific Image of Man" (1962). The famous "manifest image" vs "scientific image" distinction, with Sellars's controversial verdict that the scientific image is metaphysically prior. "In the dimension of describing and explaining the world, science is the measure of all things, of what is that it is, and of what is not that it is not." The single most quoted naturalist slogan after Quine.
• David Papineau, Philosophical Naturalism (Blackwell 1993). The cleanest contemporary statement, organized around causal closure. The core argument: physics is causally closed (physical effects have only physical causes), therefore minds (which causally affect physical bodies) must be physical, therefore physicalism.
• Daniel Stoljar, Physicalism (Routledge 2010). A careful philosophical taxonomy of the varieties of physicalism and the arguments for each.
• Barry Loewer, ongoing work on the metaphysics of physics, statistical mechanics, and the foundational status of physical laws within a naturalist framework.

By the 1990s "naturalism" had become so unmarked in academic philosophy that one rarely needed to argue for it; the burden of proof had been shifted onto its critics. The recovery of analytic theism (Plantinga, Swinburne, van Inwagen, Stump, and others) is in significant part a contest over which side bears that burden.

Major defenses

The strongest cases for metaphysical naturalism in the contemporary literature.

The causal-closure argument (Papineau)

• Premise 1: physics is causally closed. Every physical effect has a sufficient physical cause.
• Premise 2: mental events causally affect physical events (raising my arm, etc.).
• Conclusion: mental events are physical events.

The argument from physics to physicalism. Its force depends on the causal-closure premise, which Papineau argues was established empirically by the mid-twentieth-century maturation of the conservation laws.

The success-of-science argument

• Premise 1: science, operating under methodological naturalism, has been spectacularly successful in explaining phenomena that older supernaturalist frameworks failed to explain.
• Conclusion: the most parsimonious inference is that the natural order is all there is.

The structure is inference to the best explanation. The Christian counter (see below) is that the inference is too quick: methodological success does not establish metaphysical exhaustiveness.

Quine's parsimony argument

• Premise 1: a theory should posit only the entities it must to make sense of experience.
• Premise 2: natural science is our best total theory and does not need to posit supernatural entities.
• Conclusion: therefore there are no supernatural entities.

The Occamist case. Its force depends on whether our best total theory really does without supernatural commitments, which is exactly what the apologist disputes.

Sellars's scientific-image priority

The thesis that when the scientific image and the manifest image conflict, the scientific image wins. Persons, intentionality, normativity, and qualitative experience belong to the manifest image and must either be vindicated by reduction or eliminated.

Naturalized epistemology (Quine)

Epistemology as a chapter of empirical psychology. The traditional foundationalist project of justifying knowledge from outside science is abandoned; instead, we study how cognizing organisms in fact come to have reliable beliefs. The Christian critic notes that this move concedes a great deal: if epistemology is fully naturalized, the warrant for naturalism itself becomes a contingent empirical question, opening the door to Plantinga's reverse-leverage critique.

Christian apologetic critiques

The major lines of philosophical resistance to metaphysical naturalism developed in twentieth and twenty-first century Christian thought.

The Evolutionary Argument Against Naturalism (Plantinga's EAAN)

Alvin Plantinga, Warrant and Proper Function (Oxford 1993), ch. 12; Warranted Christian Belief (Oxford 2000), ch. 12; Where the Conflict Really Lies (Oxford 2011), ch. 10. The argument in compressed form:

• Premise 1: if naturalism is true, our cognitive faculties were produced by unguided evolutionary processes.
• Premise 2: unguided evolution selects for adaptive behavior, not for true belief. Adaptive behavior can be produced by many belief-desire combinations, most of which are false.
• Premise 3: therefore P(R | N&E), the probability that our faculties are reliable given naturalism and evolution, is low or inscrutable.
• Premise 4: someone who believes both N&E and that P(R | N&E) is low or inscrutable has a defeater for everything they believe, including N&E itself.
• Conclusion: the naturalist who accepts evolution has a defeater for naturalism. Naturalism is self-undermining.

See Argument from the Reliability of Reason for the dedicated hub.

The Argument from Reason (Lewis-Reppert)

C. S. Lewis, Miracles: A Preliminary Study (Bles 1947; rev. ed. 1960), ch. 3, "The Cardinal Difficulty of Naturalism." Developed in contemporary form by Victor Reppert, C. S. Lewis's Dangerous Idea (IVP 2003). The structure:

• If naturalism is true, all events are caused by non-rational physical processes.
• Acts of reasoning, where the conclusion is believed because the premises support it, require rational causation (the rational relation between premises and conclusion must itself be what produces the belief).
• Non-rational causation cannot produce rational causation in the required sense.
• Therefore naturalism cannot account for the rational causation that its own arguments presuppose.

Cousin argument to EAAN but pre-dates it by half a century and runs on different (less evolutionary, more conceptual) machinery. See Argument from Reason for the dedicated hub and C.S. Lewis for biographical context.

The Moral Argument

If metaphysical naturalism is true, there are no non-natural normative facts. Either moral facts are reducible to natural facts (descriptive accounts of preference, evolution, or social contract) or there are no moral facts at all. Both options are deeply implausible to most people, including most secular philosophers: the first commits the is-ought fallacy (Is-Ought Fallacy), the second collapses into nihilism. Theism, by contrast, grounds objective moral facts in the character and commands of a personal God.

The contemporary moral argument is associated with William Lane Craig, Reasonable Faith (Crossway, 3rd ed. 2008), ch. 4; Robert Adams, Finite and Infinite Goods (Oxford 1999); C. Stephen Evans, God and Moral Obligation (Oxford 2013); and earlier with C. S. Lewis, Mere Christianity (Bles 1952), Book I. See Moral Argument.

The Argument from Consciousness

David Chalmers, The Conscious Mind (Oxford 1996), formulates the hard problem of consciousness: even if every functional and behavioral aspect of cognition is explained by physical processes, the question of why there is subjective experience at all remains untouched. Why is it like something to be a thinking system, rather than nothing? Functional and structural explanations cannot answer this question because they leave the explanandum (subjective experience) entirely outside their reach.

Christian apologists (including Richard Swinburne, The Evolution of the Soul, Oxford 1986; J. P. Moreland, Consciousness and the Existence of God, Routledge 2008) argue that consciousness is much less surprising on theism than on naturalism: a personal Creator who makes conscious creatures in his image is the kind of cause that would produce conscious effects, whereas an impersonal physical substrate is not. See Consciousness.

The Cosmological and Fine-Tuning Arguments

Cosmological arguments (Cosmological Arguments) press the question of why a contingent natural order exists at all. Naturalism either treats the natural order as brute fact (violating principles of sufficient reason), pushes the question back to a multiverse (which itself requires explanation), or refuses the question (evading rather than answering).

Fine-tuning arguments (Fine-Tuning Argument) press the further question of why the natural order is calibrated for the emergence of life and conscious observers. Naturalism's standard response is the multiverse plus the anthropic principle, but multiverse hypotheses are themselves theoretical posits with their own evidential burdens.

The Argument from Mathematical Intelligibility

Eugene Wigner, "The Unreasonable Effectiveness of Mathematics in the Natural Sciences" (Communications on Pure and Applied Mathematics, 1960). The astonishing fact that abstract mathematical structures, formulated for purely conceptual reasons, turn out to describe the physical universe with extraordinary precision. On strict materialism, why should our minds be calibrated to apprehend the cosmos's mathematical structure? The theist has a ready answer: a rational Creator made both the cosmos and the minds that explore it. The strict materialist has a much harder problem.

The Meaning, Purpose, and Value Gap

Strict naturalism, consistently held, denies objective meaning, objective purpose, and objective value. The most honest naturalists (Rosenberg, the early Russell) accept this and call it nihilism. The less honest naturalists try to retain meaning, purpose, and value while denying the metaphysical infrastructure that would ground them. Christian apologists press: the naturalist has to choose between honest nihilism and incoherent borrowing. See Atheism Moral Neutrality Failure and Tom Holland's Dominion (Little Brown 2019) for the historical version.

The Self-Undermining Critique (Van Til, presuppositional)

Cornelius Van Til and the Reformed presuppositional tradition (Greg Bahnsen, Always Ready, Texts and Studies 1996; John Frame, Apologetics to the Glory of God, P&R 1994) argue that naturalist epistemic commitments (truth, evidence, rationality, knowledge) presuppose a transcendent order that naturalism's metaphysical commitments cannot ground. The naturalist is therefore standing on Christian capital while denying the bank that issued it.

The methodological-vs-metaphysical confusion as a rhetorical move

Worth a dedicated section because it surfaces so often in popular debate, classroom presentation, and journalism.

The typical move

A popular naturalist (Dawkins, Coyne, Krauss, the New Atheist register) argues as follows:

• Science assumes methodological naturalism.
• Science has been wildly successful.
• Religion's explanations have repeatedly been displaced by scientific ones.
• Therefore the rational, scientifically-minded person should be a metaphysical naturalist (an atheist, materialist, secularist).

What is wrong with the move

The argument equivocates between methodological and metaphysical naturalism. Methodological naturalism's success establishes that bracketing the supernatural during scientific inquiry is a productive research strategy, not that no supernatural reality exists. The two claims are logically independent. A perfectly successful methodologically-naturalist science is fully compatible with the existence of God, the soul, miracles, and the afterlife, none of which fall within science's self-chosen domain of inquiry. (Newton, Boyle, Faraday, Maxwell, Mendel, Kelvin, and many others operated under MN without holding MeN, and their science was not impoverished by the combination.)

The clean apologetic response

Three steps:

• Concede MN as a productive research strategy for natural science. Christians have no quarrel with it as such, and many Christian scientists work under it.
• Refuse the slide to MeN. MeN is a substantive metaphysical position that requires its own arguments and bears its own evidential burden. It is not delivered by science; it is a worldview added to science.
• Press the question: what argument do you have for MeN itself? The popular naturalist is usually unprepared, because they have been treating MeN as the default position rather than as a contested claim.

This single distinction reframes most of the religion-and-science debate.

Why this matters for apologetics

Three reasons metaphysical naturalism is the central worldview opponent for contemporary Christian apologetics.

Most contemporary objections to faith are downstream of it

The standard objections: the problem of evil presupposes that suffering has no purpose (which presupposes the absence of a providential agent); the argument from religious diversity presupposes that all religious claims are equally indifferent to evidence (which presupposes naturalism's framing); the argument from divine hiddenness presupposes that an evidentialist epistemology exhausts what justifies belief in God (which presupposes a naturalistically-friendly evidentialism). Naturalism is the assumed background; addressing the background often defuses the foreground objections more effectively than addressing each one in isolation.

It is not a default position

Treating MeN as the default from which other worldviews must depart is the single largest rhetorical concession in contemporary debate. The apologist's first move is usually to refuse the concession. MeN is one worldview among others, with its own metaphysical commitments, its own explanatory burdens, and its own evidential vulnerabilities. The burden of proof is mutual, not asymmetric.

Its own internal pressures are mounting

Within secular philosophy, naturalism faces serious internal pressure from the hard problem of consciousness (Chalmers), the unreasonable effectiveness of mathematics (Wigner), the irreducibility of normativity (McDowell, the late Putnam), and the self-undermining structure pointed out by Plantinga's EAAN. The liberal-naturalist response (De Caro-Macarthur) is in some ways a controlled retreat. The apologist should know these internal pressures and use them; they come from inside the secular academy and cannot be dismissed as theistic special pleading.

See also

• Methodological Naturalism, the working-rule version often confused with this one.
• Materialism, the strictest substantive form.
• Scientism, the closely related epistemological commitment.
• Consciousness, the major internal pressure point.
• Meta-Ontology, the field that investigates what "exists" even means in claims like "only natural entities exist."
• Meta-Ontological Argument for Theism, the debate-prep deployment.
• Argument from the Reliability of Reason, Plantinga's EAAN.
• Argument from Reason, the Lewis version.
• Moral Argument, the normativity critique.
• Fine-Tuning Argument and Cosmological Arguments, the cosmic critiques.
• Atheism, the typical worldview pairing.
• Christianity, the major rival worldview.
• Alvin Plantinga and C.S. Lewis, primary critics.
• Self-refutation, the structural defect EAAN identifies.