Philosophy · Contested
The Leibnizian Argument from Contingency
Gottfried Wilhelm Leibniz's argument from contingency holds that because the universe, taken as a whole, is a contingent reality whose existence is not self-explanatory, its existence requires an explanation in a necessarily existing being, distinct from the universe, whose non-existence is impossible.
The evidence explained
Leibniz articulated a version of this argument in his 1714 essay 'The Principles of Nature and Grace,' arguing from what he called the principle of sufficient reason, the claim that nothing occurs without a reason why it is so and not otherwise, to the conclusion that the sum total of contingent facts about the universe, however far back explanation is pursued through prior contingent states, cannot itself be sufficiently explained without appeal to something that exists necessarily rather than contingently, which Leibniz identifies with God.
Contemporary defenders, most notably Alexander Pruss and Richard Swinburne working from somewhat different versions of the principle, and Robert Koons applying related reasoning, argue the argument does not require explaining each individual contingent fact one by one, which could proceed to infinity, but rather asks for an explanation of the entire conjunction of contingent facts taken as a whole, an explanation which, by the nature of the case, cannot itself be another contingent fact without being included in, and thus failing to explain, the very totality in question.
The most influential objections target the principle of sufficient reason itself. Some philosophers, including J. L. Mackie and William Rowe (the latter accepting the argument's validity while doubting the truth of its central premise), have argued the strong version of the principle needed for the argument is not obviously true and may not be something we have adequate grounds to accept, particularly given that it seems to rule out brute, unexplained facts a priori rather than by evidence. Others, following a line of criticism associated with Bertrand Russell's 1948 BBC debate with Frederick Copleston, argue that treating 'the universe as a whole' as a single entity requiring explanation may commit a fallacy of composition, since a chain (or total collection) may lack a property (contingency-requiring-explanation) even if every individual link has that property, an objection Pruss and others have specifically tried to rebut with formal arguments that the fallacy-of-composition charge does not automatically apply to this kind of totality claim.
The argument remains a live topic in analytic philosophy of religion precisely because it turns on the truth and proper formulation of the principle of sufficient reason, a genuinely contested metaphysical principle rather than a matter that can be settled empirically, and different formulations of the principle (strong versions requiring an explanation for absolutely every fact, versus weaker versions applied only to contingent existence as such) yield significantly different degrees of argumentative vulnerability to the standard objections.
What it does show
- • If a sufficiently strong and defensible version of the principle of sufficient reason is true, the existence of contingent reality as a whole plausibly requires explanation by a necessarily existing being.
- • The argument identifies a genuine philosophical puzzle about whether an infinite regress of contingent explanations can ever constitute a complete explanation of contingent existence as such.
What it does not show
- • It does not establish the truth of the principle of sufficient reason, which remains a contested metaphysical premise rather than a self-evident axiom.
- • It does not by itself establish that the necessary being in question has the specific attributes traditionally ascribed to the God of any particular religious tradition.
- • It does not refute the possibility, defended by some philosophers, that the universe or some more basic physical reality is itself the necessary being or brute fact in question.
Primary sources and literature
- G. W. Leibniz, 'The Principles of Nature and Grace, Based on Reason' (1714)Classic original statement of the argument.
- Alexander Pruss, The Principle of Sufficient Reason: A Reassessment (2006)Leading contemporary defense of the argument and the principle.
- Bertrand Russell and Frederick Copleston, BBC Radio Debate on the Existence of God (1948)Classic exchange raising the fallacy-of-composition objection.
- William Rowe, The Cosmological Argument (1975)Careful philosophical treatment sympathetic to the argument's validity but skeptical of its key premise.
Where scholars disagree
Philosophers agree the argument is logically valid given its premises but disagree sharply over whether the principle of sufficient reason, in the strength required by the argument, is true or adequately justified.
For further study
Primary and secondary sources on both sides of this question. Reading the strongest opposing case is part of the work, not a concession.
The Blackwell Companion to Natural Theology — William Lane Craig and J. P. Moreland (eds.)
The reference volume: long, technical chapters defending each major theistic argument, with the best statements of the cosmological, fine-tuning, moral, and ontological arguments.
Five Proofs of the Existence of God — Edward Feser
Classical (Aristotelian, Neo-Platonic, Thomistic) arguments defended in analytic form, with sustained attention to what the conclusions do and do not establish.
The Miracle of Theism — J. L. Mackie
The best twentieth-century atheist engagement with the theistic arguments; read it to see which objections actually bite.
Arguing About Gods — Graham Oppy
A rigorous skeptical assessment arguing that no theistic argument succeeds as a proof; the standard opposing benchmark.
The Existence of God — Richard Swinburne
Builds a cumulative probabilistic case rather than a single deductive proof — useful for seeing how arguments combine.