ris3n's Apologetics Codex

Argument

Contingency Argument

Intro

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Look around at anything in the room. A chair, a cup, a tree out the window, your own hand. Each of these could have not existed. There is nothing built into the nature of chair that says it had to be. Its existence depends on something outside of itself: the wood, the carpenter, the tree, the soil, the sun. Things like this, things that could have failed to exist, philosophers call contingent.

Now stack all the contingent things in the universe together. The universe itself is the same kind of thing. It exists, but it could have not existed. There is nothing in the bare idea of universe that demands it be. So the same question applies to the whole stack: why is there a universe at all rather than nothing?

You cannot answer that by pointing to more contingent stuff. "The universe came from a prior universe" just pushes the question back. "It came from a quantum vacuum" names another contingent thing. "It's been here forever" still does not explain why an eternal contingent thing should exist rather than not exist. A long chain of borrowers is still all borrowers. Somewhere the chain has to land on something that does not need a loan, something that exists in itself, by the necessity of its own nature.

That is a necessary being. Not a thing that happens to exist; a thing that cannot not exist. There is only one kind of candidate for that role, and it is roughly what every classical tradition has called God.

Notice what this argument does not need. It does not need a beginning of the universe. Even a universe that has always existed is still a contingent universe. It does not need quantum physics or cosmology. It needs only one principle: things that exist have reasons for existing. That principle is what makes science possible. Deny it, and you are denying that "why?" is ever a real question.

The quick reply in conversation: "Anything that could have failed to exist needs a reason for existing. The universe could have failed to exist. So what is the reason? And whatever the reason is, if it could also have failed to exist, it needs a reason too. The chain only ends with something that cannot fail to exist."

In full

The contingency argument reasons from the existence of contingent beings (things that could have failed to exist) to a Necessary Being whose existence is grounded in its own nature. Distinct from the Kalam Cosmological Argument in that it does not require the universe to have a temporal beginning, even an eternal universe would still be a contingent collection requiring an external explanation. The Leibnizian formulation runs through the Principle of Sufficient Reason; Aquinas's Third Way runs through the impossibility of universal contingency. Both converge on the same conclusion: a Necessary Being identified with God.

Argument structure

# Premise
P1 Everything that exists has an explanation of its existence, either in the necessity of its own nature or in an external cause. (Principle of Sufficient Reason)
P2 The universe (and everything in it) is contingent, it could have failed to exist.
P3 A collection of contingent beings is itself contingent and cannot explain its own existence.
P4 Therefore the universe's existence requires an external cause.
P5 The external cause must itself be non-contingent, a necessary being whose existence is grounded in its own nature.
C Therefore a Necessary Being exists, which is the cause of all contingent existence, identified by Christians as God.

Form

Deductive, classical metaphysical reasoning. The argument is valid given PSR (P1) and the contingency of the universe (P2-P3). It runs even on a past-eternal universe, making it more robust than Kalam against multiverse and eternal-cosmology defenses. The argument's force is felt at P1 (PSR) and P3 (whole-of-collection contingency); both are well-defended in contemporary analytic literature.

P1, Principle of Sufficient Reason: everything that exists has an explanation

Affirmative case (second-order arguments)

  1. Presupposed by all rational inquiry. Science, history, philosophy all presuppose that things are explicable, that "why does X exist?" is always a meaningful question with a real answer. To deny PSR is to abandon the explanatory enterprise. (Pruss, The Principle of Sufficient Reason, 2006, ch. 1.)
  2. Weak PSR is sufficient. The argument needs only the weak form: every contingent fact has an explanation. The strong form (every fact, including necessary truths, has an explanation) is more disputed and not required. The weak form is far more secure. (Pruss; Koons, Realism Regained, 2000.)
  3. The "modal-collapse" objection to PSR is question-begging. The famous Van Inwagen objection, that PSR entails that contingent facts are necessary, only goes through on certain controversial readings of "explanation." Pruss has demonstrated multiple PSR-formulations that avoid modal collapse (libertarian-free-action explanations, agent-causal explanations, conceptual reanalysis of "explanation"). The objection is not a refutation; it's a constraint on PSR-formulation.
  4. Selective application is special pleading. The opponent who holds PSR for ordinary explanation but denies it at cosmic scale must justify the carve-out. No principled reason to deny PSR only at the boundary has ever been provided.

Anticipated objections

  1. "Brute facts exist, some things are simply unexplained." Russell's "the universe is just there" / Hume's denial of necessary connections / contemporary contingentists.
  2. "PSR entails modal collapse." Van Inwagen, An Essay on Free Will (1983); Bennett.
  3. "Quantum events show PSR is empirically false." Indeterministic events have no determining cause.
  4. "PSR is unverifiable / metaphysically extravagant." Logical-positivist line; no empirical content.

Rebuttals

  1. "Brute fact" is unfalsifiable and ad hoc. It is not a substantive metaphysical position; it is a refusal to engage the explanatory question. Granting it for the universe but denying it for putative theistic alternatives is special pleading. The opponent should explain why the cosmos is the unique exception to a principle that operates universally elsewhere. Failure mode: special pleading.
  2. Modal-collapse moves are answerable. Pruss's defense (PSR, ch. 4-7) shows the objection requires a deterministic-explanation reading of PSR that the libertarian-theist can reject. Agent-causal explanations satisfy PSR without entailing necessity (the Necessary Being's free choices have explanations, namely, the agent's reasons, without making the choices themselves necessary). Failure mode: conflating explanation with entailment.
  3. Indeterministic causation is still causation. Quantum events have probabilistic-causal structure; "no deterministic cause" is not "no cause." PSR demands explanation, not determination. (See P1 of Kalam Cosmological Argument for the parallel response.) Failure mode: equivocation on "cause".
  4. Logical-positivist verification criterion is self-defeating. The verification principle itself is unverifiable; the school collapsed on this objection (Hempel, Popper, Quine all delivered the death-blows by mid-century). Demanding empirical verification of metaphysical principles assumes a verificationism that no philosopher of science holds today. Failure mode: self-defeating epistemology.

Live-cite kit

  • Scripture: Romans 11:36 ("from Him and through Him and to Him are all things"); Colossians 1.16-17 ("in Him all things hold together"); Acts 17:25, 28
  • Scholarly: Leibniz, Monadology §32; Principles of Nature and Grace §7-8; Pruss, The Principle of Sufficient Reason (2006); Koons, Realism Regained (2000); Pruss & Rasmussen, Necessary Existence (2018); Della Rocca, "PSR" (Philosophers' Imprint, 2010)
  • Aphorism: "Either everything has an explanation, or science was always making an exception for itself."

Tactical notes

  • Defend the weak PSR, not the strong. The strong form invites modal-collapse worries that don't help the argument.
  • Lead with "presupposed by science" if the opponent is naturalist, it makes the asymmetry of denying PSR vivid.
  • Do NOT defend determinism. PSR is compatible with libertarian free will (agent-causation satisfies PSR).
  • Force-commit move: "Do you grant that 'why does X exist?' is always a meaningful question? If yes, you have PSR. If no, why is the cosmos uniquely exempt?"

P2-P3, The universe (and any collection of contingent beings) is contingent

Affirmative case (second-order arguments)

  1. Every observed thing is contingent. Stars, planets, organisms, atoms, fundamental particles, all could have failed to exist; all came into being and will pass out of being on cosmological / thermodynamic timescales. The contingency of every part is well-established empirically.
  2. Cosmological contingency: physical constants could have been otherwise. The standard model has ~25 free parameters; the cosmological constant could have differed; the laws themselves are not logically necessary. Whatever the universe's specific configuration is, it is one of an enormously larger space of coherent alternatives that could have obtained. (See Fine-Tuning Argument.) This is a strong empirical mark of contingency.
  3. Whole-of-collection contingency follows from part contingency for the right kind of property. Pruss & Koons: contingency is not an "additive" property like color or weight (Hume's worry); it is a modal status, could-fail-to-exist. If every member of the collection could fail, the collection itself could fail (the empty conjunction is logically possible). The whole has no resources outside its members to ground necessity. (Pruss, PSR; Koons, Realism Regained.)
  4. The universe shows none of the marks of necessity. Necessary existents have their existence by their nature, their non-existence is logically impossible. No physical theory has ever shown this for the universe; no philosopher has produced a defensible account on which the specific cosmos we inhabit is metaphysically necessary. The "universe is necessary" move is a placeholder, not an argument.

Anticipated objections

  1. "Hume's compositional fallacy: the universe-as-a-whole need not inherit the contingency of its parts." A pile of stones can have properties no individual stone has.
  2. "The universe (or some basic substrate, quantum vacuum, multiverse) could be necessary." Russell-style "brute" or substantive-necessity moves.
  3. "P2 is unverifiable, we can't see the alternatives." How do we know the universe could have failed to exist?
  4. "Necessity is a confused notion when applied to physical reality." Quine-style skepticism about modal categories.

Rebuttals

  1. The composition-fallacy charge is itself fallacious here. Composition fallacies fail when the property in question is not closed under aggregation (e.g., "every part is small" doesn't entail "the whole is small"). But contingency is closed under aggregation: if every part could fail, the whole could fail (by parts simultaneously failing). This is not composition; it is modal logic. The whole-of-contingents is contingent. (Pruss, PSR, ch. 16.) Failure mode: misapplied composition charge.
  2. "The universe could be necessary" requires positive argument, not just possibility. No physicist or philosopher has ever derived the universe's specific configuration from its essence; none has shown its non-existence is contradictory. The proposal floats. Even granted, a necessary universe would be either (a) so specifically necessary that quantum-mechanical indeterminism is illusory (which contradicts physics) or (b) the multi-verse-of-all-possible-worlds (in which case our specific universe is contingent on which sub-region we're in, multiverse defers the contingency, doesn't dissolve it). Failure mode: contingency-deferral.
  3. The verifiability complaint cuts both ways. The opponent who denies P2 is also making a modal claim (the universe couldn't have been otherwise) without empirical verification. Modal claims are settled by metaphysical analysis, not direct empirical observation. The empirical evidence, laws with free parameters, alternatives describable by physics, points strongly to contingency.
  4. Quine's modal skepticism is a niche position contradicted by mainstream analytic metaphysics. Modal logic (Kripke, Plantinga, Lewis) is now standard apparatus. Necessity / contingency are well-formed philosophical categories with rich technical literature. The Quinean dismissal is a 1950s position that did not survive the modal turn.

Live-cite kit

  • Scripture: Genesis 1.1 ("In the beginning God created", created things have a beginning; the Creator does not); Hebrews 1:11 (heavens "perish, but You remain"); Psalm 102:25-27 (created things change; God is the same)
  • Scholarly: Pruss, PSR (2006), ch. 16-17; Koons, Realism Regained (2000); Pruss & Rasmussen, Necessary Existence (2018); Plantinga, The Nature of Necessity (1974); Brian Leftow, God and Necessity (2012)
  • Aphorism: "A pile of contingencies, however large, is still a contingency."

Tactical notes

  • Get the opponent to distinguish part contingency from whole contingency before they can deploy Hume's composition objection. Once distinguished, the modal point about closure under aggregation lands.
  • If the opponent goes "necessary universe," ask: "By what argument? What property of the universe is supposed to entail its existence?" Force them to defend.
  • Do NOT defend a temporal beginning of the universe. That's Kalam's terrain. The contingency argument runs even on past-eternal cosmology. Don't carry Kalam's load.
  • Force-commit move: "Is there a possible world in which the universe does not exist? If yes, P2 is granted. If no, defend that claim."

P4-P5, The cause must itself be a Necessary Being

Affirmative case (second-order arguments)

  1. Regress termination. A series of contingent causes, each requiring further explanation, must terminate in something whose explanation is intrinsic, i.e., in a being whose existence is grounded in its own nature. Any other terminus (brute fact, infinite regress) violates PSR. (Aquinas, ST I.2.3 ad 7; Leibniz, Monadology §37-38.)
  2. A Necessary Being's existence is its essence. Ipsum esse subsistens: the Necessary Being is identified by classical theism as the being in which essence is identical with existence. Aseity, self-existence, is the fundamental divine attribute. (Aquinas, ST I.3.4; see Ipsum Esse Subsistens, Actus Purus, Divine Simplicity.)
  3. Conceptual properties of the Necessary Being match classical theism. Uncaused, immaterial (matter is contingent), eternal (timeless), unique (two Necessary Beings would limit each other and thus not be self-sufficient), and the source of all derivative being. The conceptual cluster is the divine attribute-cluster of classical theism.

Anticipated objections

  1. "The Necessary Being might not be God, it might be the universe or a brute substrate." Russell-style; or "necessary impersonal substrate" moves.
  2. "This proves at most a deistic First Cause, not the Christian God." Standard challenge: bare necessity doesn't get to a personal, moral, redemptive God.
  3. "Why a necessary being rather than a necessary fact or law?" Process / structuralist alternatives.

Rebuttals

  1. The Necessary Being cannot be the universe (already shown contingent in P2-P3) and cannot be a brute substrate (because brute substrates are contingent posits, they could have been otherwise). A genuinely necessary being has its existence by its nature; this rules out anything whose specific configuration could differ. The universe and any contingent substrate fail this test. The Necessary Being must be characterized by aseity, and aseity points toward a being whose nature is existence.
  2. The "deistic First Cause" challenge is correct as stated, and not a defeater. The contingency argument is one stage in a Cumulative Case for Christian Theism. It establishes a Necessary Being with the conceptual properties of classical theism; further argument (moral, historical-Resurrection, comparative-religion) gets to the specifically Christian God. The standalone argument doesn't try to do all the work; it does its piece well.
  3. "Necessary fact" or "necessary law" requires a substrate to instantiate it. Laws are abstract structures; they need concrete instantiation. The platonic move ("uninstantiated necessary law") faces its own metaphysical challenges (how do abstract objects do causal work?). The classical-theist account, Necessary Being whose nature is the source of all contingent being, is more parsimonious and explanatorily powerful. (Plantinga, Does God Have a Nature?; Leftow, God and Necessity.)

Live-cite kit

  • Scripture: Exodus 3.14 ("I AM WHO I AM", the divine self-disclosure as Being itself); Acts 17:24-28 (God who made the world doesn't dwell in temples, He's the source); Revelation 1:8 ("the Alpha and the Omega")
  • Scholarly: Aquinas, ST I.2.3 (Third Way), I.3.4 (essence-existence); Leibniz, Monadology §32-39; Plantinga, Does God Have a Nature? (1980); Leftow, God and Necessity (2012); Feser, Five Proofs of the Existence of God (2017); Edward Feser, Aquinas (2009)
  • Aphorism: "Nothing contingent grounds itself; the buck has to stop at I AM."

Tactical notes

  • Lead with regress-termination if the opponent is philosophically sophisticated; lead with "the Necessary Being's properties match the classical-theist God" if the opponent is theologically engaged.
  • Do NOT defend specifically Christian (Trinitarian) theism on this premise. That is downstream work for Christian God is the Only True God. Here, only get to the Necessary Being.
  • Force-commit move: "Granted a Necessary Being, what positive properties must it have? Walk through them with me." Lead them through aseity → immateriality → eternality → uniqueness.

Conclusion

Therefore a Necessary Being exists, which is the cause of all contingent existence. The conclusion follows by valid deductive inference from PSR + universe-contingency + necessary-being properties. The Christian identification of this Necessary Being with God depends on the further-developed cumulative case (see Christian God is the Only True God, Cumulative Case for Christian Theism).

Master objections to the argument as a whole

  1. "This is just god-of-the-gaps in fancy clothing." Reply: god-of-the-gaps fills explanatory gaps with God until a naturalistic explanation arrives. Contingency-argument runs from the structural fact of contingent existence, no future-physics could fill the explanatory role of a Necessary Being, because future-physics would itself be contingent and require explanation.
  2. "Even granted, you've reached only an abstract metaphysical posit, not a worship-worthy God." Reply: correct as a standalone, the argument is one stage. The Necessary Being's conceptual properties (aseity, immateriality, eternity, uniqueness) constrain candidates; combined with Moral Argument, Argument from the Resurrection, and Christian God is the Only True God, the cumulative case identifies this Necessary Being with the Christian God.
  3. "The argument is question-begging, assuming there must be an ultimate explanation." Reply: PSR is the assumption, and PSR is itself widely defended (see P1 affirmative case). Denying PSR has high costs; affirming it commits one to the contingency conclusion. The dialectical landscape is well-mapped.
  4. "Multiverse, every possible universe exists; none requires explanation." Reply: multiverse is itself either contingent (then what grounds it?) or necessary (then defend that claim, and face the question why this multiverse-with-these-laws exists rather than another). Multiverse defers; doesn't dissolve.

Tactical opening / closing

Opening line: "Even on a past-eternal universe, contingent things require explanation. Want to walk through what kind of explanation?"

Closing landing strip: "A Necessary Being whose nature is existence is what 'God' has always meant in classical theism. The argument doesn't get you all the way to the Trinity, but it gets you to the kind of being who could be the God of the Trinity. The next question is whether He's revealed Himself. (Resurrection?)"

Aquinas's Third Way (textual anchor)

"We find in nature things that are possible to be and not to be… but it is impossible for these always to exist, for that which is possible not to be at some time is not… If everything is possible not to be, then at one time there could have been nothing in existence… Therefore, not all beings are merely possible, but there must exist something the existence of which is necessary." (Summa Theologiae I, q.2, a.3)

The full per-premise debate-prep treatment of Aquinas's Third Way (with its distinct premises and per-se-regress logic) is at Third Way - Contingency. This page is the broader contingency-argument hub and treats both the Aquinas and Leibnizian forms.

Connection to Scripture

Patristic / scholarly note

Classical / patristic / medieval:

  • Avicenna (Metaphysics IX, 11th c.), essence-existence distinction; Aquinas inherits and Christianizes
  • Maimonides (Guide for the Perplexed II.1), Jewish parallel
  • Aquinas (Summa Theologiae I.2.3, Third Way; I.3.4 essence-existence), the locus classicus
  • Bonaventure, Franciscan parallel formulations

Modern:

  • Gottfried Leibniz, Monadology §32-39; Principles of Nature and Grace §7-8 (the canonical PSR-formulation)
  • Samuel Clarke, A Demonstration of the Being and Attributes of God (1705)
  • Alvin Plantinga, The Nature of Necessity (1974); Does God Have a Nature? (1980)
  • Robert Koons, Realism Regained (2000)
  • Alexander Pruss, The Principle of Sufficient Reason (2006); Necessary Existence (with Rasmussen, 2018)
  • Edward Feser, Five Proofs of the Existence of God (2017), ch. 5
  • Brian Leftow, God and Necessity (2012)
  • Joshua Rasmussen, Necessary Existence (2018); How Reason Can Lead to God (2019)

Critics:

  • David Hume, Dialogues Concerning Natural Religion (1779)
  • Bertrand Russell, Why I Am Not a Christian (1927); BBC debate with F. C. Copleston (1948)
  • J. L. Mackie, The Miracle of Theism (1982)
  • Peter van Inwagen, An Essay on Free Will (1983); modal-collapse objection
  • Graham Oppy, Arguing about Gods (2006)

See also