Argument

Ontological argument

Overview

In the philosophy of religion, an ontological argument is a deductive philosophical argument, made from an ontological basis, that is advanced in support of the existence of God. Such arguments tend to refer to the state of being or existing. More specifically, ontological arguments are commonly conceived a priori in regard to the organization of the universe, whereby, if such organizational structure is true, God must exist.

The first ontological argument in Western Christian tradition was proposed by Saint Anselm of Canterbury in his 1078 work, Proslogion (Latin: Proslogium, lit. 'Discourse [on the Existence of God]'), in which he defines God as "a being than which no greater can be conceived," and argues that such a being must exist in the mind, even in that of the person who denies the existence of God. From this, he suggests that if the greatest possible being exists in the mind, it must also exist in reality, because if it existed only in the mind, then an even greater being must be possible – one who exists both in mind and in reality. Therefore, this greatest possible being must exist in reality.

While Anselm's 11th-century argument is a cornerstone of Western scholasticism, it was preceded by the "Proof of the Truthful" (Burhan al-Siddiqin) developed by Ibn Sina (Avicenna) in the early 11th century. Unlike Anselm’s purely conceptual approach, Ibn Sina’s proof is built on a logical framework of contingency and necessity. He argued that since the collection of all "possible beings" (entities that require a cause for their existence) must itself have a cause, this sequence must terminate in a "Necessary Existent" ('Wajib al-Wujud') that exists by its own essence rather than through external causation. Scholars such as Herbert Davidson note that although both thinkers reached their ontological conclusions independently, Ibn Sina’s systematic derivation provided a distinct metaphysical foundation that influenced later medieval and modern philosophy.

Seventeenth-century French philosopher René Descartes employed a similar argument to Anselm's. Descartes published several variations of his argument, each of which center on the idea that God's existence is immediately inferable from a "clear and distinct" idea of a supremely perfect being. In the early 18th century, Gottfried Leibniz augmented Descartes's ideas in an attempt to prove that a "supremely perfect" being is a coherent concept. A more recent ontological argument was formulated by Kurt Gödel in private notes, using modal logic. Although he never published or publicly presented it, a version was later transcribed and circulated by Dana Scott. Norman Malcolm also revived the ontological argument in 1960 when he located a second, stronger ontological argument in Anselm's work; Alvin Plantinga challenged this argument and proposed an alternative, based on modal logic. Attempts have also been made to validate Anselm's proof using an automated theorem prover. Other arguments have been categorised as ontological, including those made by Islamic philosophers Mulla Sadra and Allama Tabatabai.

Just as the ontological argument has been popular, a number of criticisms and objections have also been mounted. Its first critic was Gaunilo of Marmoutiers, a contemporary of Anselm's. Gaunilo, suggesting that the ontological argument could be used to prove the existence of anything, uses the analogy of a perfect island. Such would be the first of many parodies, all of which attempted to show the absurd consequences of the ontological argument. Later, Thomas Aquinas rejected the argument on the basis that humans cannot know God's nature. David Hume also offered an empirical objection, criticising its lack of evidential reasoning and rejecting the idea that anything can exist necessarily. Immanuel Kant's critique was based on what he saw as the false premise that existence is a predicate, arguing that "existing" adds nothing (including perfection) to the essence of a being. Thus, a "supremely perfect" being can be conceived not to exist. Finally, philosophers such as C. D. Broad dismissed the coherence of a maximally great being, proposing that some attributes of greatness are incompatible with others, rendering "maximally great being" incoherent.

Contemporary defenders of the ontological argument include Alvin Plantinga, Yujin Nagasawa, and Robert Maydole.

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

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That gives rise to these eternal, and usually mistaken, contentions on necessity and contingency, on the possible and the impossible. But provided that it is understood that necessity and possibility, taken metaphysically and strictly, depend solely upon this question, whether the object in itself or that which is opposed to it implies contradiction or not; and that one takes into account that contingency is…
Gottfried Wilhelm Leibniz, Theodicy Essays on the Goodness of God, the Freedom of Man and the Origin of Evil
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But if the possibility of such a being is thus demonstrated, its existence is also proved; for we may then assert that, of all possible beings there is one which possesses the attribute of necessity—in other words, this being possesses an absolutely necessary existence. All illusions in an argument are more easily detected when they are presented in the formal manner employed by the schools, which we now proceed to…
Immanuel Kant, The Critique of Pure Reason
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But in comparison with an unalloyed identity, every defining term as such seems to the understanding to be only a limit and a negation: every reality accordingly must be taken as limitless, _i.e._ undefined. Accordingly God, when He is defined to be the sum of all realities, the most real of beings, turns into a _mere abstract._ And the only term under which that most real of real, things can be defined is that of…
Georg Wilhelm Friedrich Hegel, The Logic of Hegel
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Ontological argument

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