Necessary Existence — Pruss and Rasmussen

A quick summary with 7 key thoughts

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The book represents a significant contribution to contemporary metaphysics and philosophical theology, offering novel arguments for the existence of a necessary being while engaging with modal logic, contemporary metaphysics, and classical philosophical arguments.

The authors begin by establishing a conceptual framework for understanding necessary existence. A necessary being is defined as something that exists in all possible worlds — its non-existence is metaphysically impossible. This contrasts with contingent beings, which exist in some possible worlds but not others. The book’s central thesis is that there must be at least one necessary being to explain the existence of contingent reality.

One of the book’s most innovative contributions is its development of the “Modal Uniformity Principle” (MUP). This principle suggests that similar things tend to have similar modal profiles — if something is contingent, similar things tend to be contingent as well. The authors use this principle to argue that the fundamental reality underlying our universe must necessarily exist, as it would be arbitrary for it to be contingent.

A significant portion of the book deals with abstract objects and their relationship to necessary existence. The authors argue that if abstract…