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Leibnizian cosmological argument

This page is a deep dive on one branch of the broader cosmological case. Leibniz's distinctive focus is not mainly temporal beginning, but contingency and explanation.

The core insight

Look around: you did not have to exist. This page did not have to exist. The laws of physics did not have to be exactly what they are. There is a vast field of facts that could have been otherwise. Philosophers call them contingent facts.

This is the question Gottfried Wilhelm Leibniz made famous: why is there something rather than nothing? Not only "why this galaxy," but why any contingent reality exists at all.

Leibniz's answer begins with a simple intuition: if something could have failed to exist, then it is reasonable to ask why it exists instead of not existing.

The lever: principle of sufficient reason

Very roughly: for contingent truths, there is an explanation of why they hold rather than not. We explain this more fully on Principle of sufficient reason.

Leibniz then asks what explains the whole package of contingent reality. Not one more contingent fact inside the package, because that would only push the question back a step. The explanation must be of a different kind: something that does not need an external explanation because it exists necessarily.

That is why this argument points to what classical theists call God: a necessary being, not one more item in the world, but the ground that explains why contingent things exist at all.

Why this version matters

  • It reaches deeper than questions about a first moment in time.
  • It targets the whole ensemble of contingency, not one isolated event.
  • It explains why the universe is not well-described as brute fact piled on brute fact.

Objections answered

Does the PSR ask too much?

Only if it is stated carelessly. The force of the Leibnizian argument does not require that every fact be explained in the strongest imaginable way. It requires the much more plausible claim that contingent reality is not explained simply by existing.

Why can't the totality of contingent things explain itself?

Because bundling contingent facts together does not remove their contingency. The whole package is still the sort of thing that could have been otherwise. So the demand for explanation remains.

How this differs from Kalām

Kalām often foregrounds a beginning in time. Leibniz's angle is more directly about contingency and sufficient reason. The two arguments are allies, but they are not the same argument.

Verdict

The Leibnizian form of the cosmological argument presses a sharp question: why is there any contingent reality at all? Its answer remains powerful because one more contingent fact never explains the whole. A necessary being explains the whole better.

References (starting points)

  1. Leibniz’s cosmological argument (lecture notes, PDF)
  2. Cosmological argument — Wikipedia (overview)
  3. Cosmological Argument — Stanford Encyclopedia of Philosophy
  4. Leibniz’s ontological and cosmological arguments — chapter in The Cambridge Companion to Leibniz

See also