The principle of sufficient reason

the long version

"The Principle of Sufficient Reason (PSR) says that all contingent facts must have explanations. In this volume, the first on the topic in the English language in nearly half a century, Alexander Pruss examines the substantive philosophical issues raised by the PSR, which currently is considered primarily within the context of various cosmological arguments for the existence of God. Discussing several forms of the PSR and selected historical episodes from Parmenides, Aquinas, Leibniz, Hume, and Kant, Pruss defends the claim that every true contingent proposition must have an explanation against major objections, including Hume's imaginability argument and Peter van Inwagen's argument that the PSR entails modal fatalism."--Jacket.