Necessary Being

A Necessary Being is a being whose existence is not contingent on anything else and that could not have failed to exist. The notion is central to nearly every form of the Cosmological Argument and to the modal version of the Ontological Argument.

In the Cosmological Argument from contingency, the necessary being is the terminus of the explanatory chain: the existence of contingent beings demands an explanation; the chain of contingent explanations cannot be self-sustaining; therefore there must exist something whose explanation is internal to itself, that is, a necessary being. Theists identify this being with God.

In the modal Ontological Argument in Alvin Plantinga‘s reformulation, the relevant claim is that a maximally great being would have to exist in every possible world, not merely some, and that maximal greatness includes existence and the standard divine attributes.

What unites the two uses is the modal logic. A necessary being, in the technical sense, exists in every possible world. The disagreements between theists and atheists about the cosmological and ontological arguments turn, almost without exception, on whether such a being is possible at all and on what kind of explanation, if any, is required for the totality of contingent fact. These are not questions on which philosophers expect to reach consensus.