The Principle of Sufficient Reason: A Reassessment

by Alexander R. Pruss

The Principle of Sufficient Reason (PSR) says that all contingent facts must have explanation. In this 2006 volume, which was the first on the topic in the English language in nearly half a century, Alexander Pruss examines the substantive philosophical issues raised by the Principle Reason. Discussing various forms of the PSR and selected historical episodes, from Parmenides, Leibnez, and Hume, 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. Pruss also provides a number of positive arguments for the PSR, based on considerations as different as the metaphysics of existence, counterfactuals and modality, negative explanations, and the everyday applicability of the PSR. Moreover, Pruss shows how the PSR would advance the discussion in a number of disparate fields, including meta-ethics and the philosophy of mathematics.

Genres: Philosophy, Metaphysics, Theology, Religion

350 pages, Paperback

First published March 20, 2006

About the author

Canadian philosopher, mathematician. Pruss's philosophical thought reflects Christian orthodoxy. He is a Roman Catholic and a member of the Society of Christian Philosophers.

Pruss defends the principle of sufficient reason (PSR), claiming that it is self-evident, and arguing that the rejection of PSR creates problems in epistemology, modality, ethics, and even evolutionary theory.

Pruss is a critic of David Lewis's "extreme modal realism," and instead gives "a combined account" of Leibnizian and Aristotelian modality, which integrates the "this-worldly capacities" of the Aristotelian view and Leibniz's account of possible worlds as thoughts in the mind of God.

Reviews

[Nelson · Rating 4 out of 5]

This is a good book. Very technical so I would only recommend this to those who are highly educated in philosophy and who have a decent grasp of formal logic. I absolutely would not recommend this to a beginner who is looking into the PSR.

In the first section, Pruss offers a detailed history and definition of the PSR. In the second section, he thoroughly explores various attacks on the PSR and meticulously deconstructs, critiques and refutes them. In the third, he offers justifications/assesses various justifications of the PSR.

Sections one and two were brilliant, but two was little tedious (perhaps reasonably so as the critiques of the PSR were technical and required a requisitely technical response). But I do think he put a bit too much stock in the objections than was proportional to their force however and he was too modest in his rejection of them.

Section 3 was a decent defence of the PSR however it was very very modest (and characteristically technical). He explores various arguments for the sufficiency of the PSR (and assesses the plausibility of them also). He also provides defences to the criticisms of those justifications and assesses their ultimate plausibility. The conclusion, it should be noted, was unduly modest in my opinion (but perhaps that’s because I simply lack a deep appreciation for the force of the objections).

In all a good book that does a very thorough job of defending and justifying the PSR. Truly an essential work on the subject and deserving of high praise for its depth and for the genius of the author. But if you are looking for a dramatic and compelling defence of the PSR I would look elsewhere. I realistically won’t read this book again (although I liked it). I much prefer the book ‘Necessary Existence’.

[Adam Chandler · Rating 4 out of 5]

Pruss argues the the Principle of Sufficient Reason (PSR) exists despite things like the modern philosophical objects from free will and the physical objections from quantum mechanics. He does good work in addressing the concerns and shows that no objection is a defeater of the PSR but I find his support for the PSR is somewhat lacking. Pruss brings forward a number of logical arguments for the PSR but they are not definitive, as he admits, so he relies on the self-evident claim that everything has a cause except for something necessary. It is my hope to find something more concrete to support the PSR. At the very least, this book is incredibly useful in understanding the PSR in relation to causation in philosophical conversation today.

[Jared Mindel · Rating 4 out of 5]

Very good. I only give it 4 stars because some of it could be much clearer.