The ontological argument is one of the earliest theological proofs for the existence of the Abrahamic monotheistic God. In the late classical period a Catholic monk and patron saint named St. Anselm of Canterbury (1033/4-1109 A.D.) is widely considered to be its original author. He propounds upon this idea in his meditative dialog Proslogion (English: Discourse on the Existence of God). As the name suggests this argument is ontologically based on a priori premises; in other words, based on reason and not empirical observation (a posteriori). While it has been touted by modern theist as a definitive proof for God existence it has also gained significant criticism. Both theist and non-theist have condemned it for its specious argumentation, abusing several fallacies in addition to an unethical use of semantics.

The universe is full of magical things patiently waiting for our wits to grow sharper.

– Eden Phillpotts

The purpose of this thesis is to critically analyze and critique the ontological argument in terms of its validity and sound logic. Proving the existence of God is obviously a huge undertaking so lets explore what could have inspired Anselm to develop it. The concept of predicates and properties has been debated-over long before St. Anselm’s time, predating even before Christendom. Isagoge, by the Roman philosopher Porphyry of Tyre distinguishes predicates in his tree of porphyry or states of being. In one of Aristotle’s earliest works, The Organon, he distinguishes predicates into four separate categories definition, property, genus, and accident. No doubt St. Anselm was inspired by the writings of these earlier philosophers but we can not ignore his monasticism. St. Anselm was a monk so we can assume with a degree of certainty it was his dogmatism that roused his initial attempt at grounding his ideology ontologically. In the following syllogism Anselm lays out his ontological argument (Prosologium (Ch. 3)),

(1) By definition, God is a being that which none greater can be imagined.
(2) A being that necessarily exists in reality is greater than a being that does not necessarily exist.
(3) Thus, by definition, if God exists as an idea in the mind but does not necessarily exist in reality, then we can imagine something that is greater than God.
(4) But we cannot imagine something that is greater than God.
(5) Thus, if God exists in the mind as an idea, then God necessarily exists in reality.
(6) God exists in the mind as an idea.
(7) Therefore, God necessarily exists in reality.

The ontological argument is intended to be persuasive with its simplicity and validity, although it may lead to apriorism. A priori falsehoods can be assumed if they rest on principles alone. Principles alone cannot guarantee an empirical truth. There are things about the universe that we simply do not understand and defy all modern notions of logic and mathematical reason. This isn’t to make an argument from ignorance, it’s rather an err of caution when attempting to prove such an ambitious metaphysical claim. The ontological argument could be saved if we grant the definition of (1). Unfortunately we can’t afford to be altruistic. Firstly, there is no ontological commitment to accepting such an assertion. I see no reason why we should accept the definition of (1) as its recursive and principally unfounded. Furthermore, (1) is question begging as it implies the existence of God by initially defining the existence of his quiddities (greatness/necessity). This would mean that the conclusion is implied within the initial premise making (1) question begging.

In (2) through (5) Anselm makes a crucial mistake by trying to assert a proof by contradiction (reductio at absurdum); however, contradictions could exist in the mind despite not being objectively real. Because unlike objective reality the human mind is filled with contradictory statements and ideas. Def: To be logically committed to the assertion of some statement, S, and its denial, not-S, at the same time (Mayes n.d.). Take the following operation ¬(p ∧ ¬p), which describes a contradiction. By definition a contradiction can exist (a priori). We are just unable to account for its meaning synthetically. While proof by contradictions are valid to utilize in some arguments this wouldn’t be the case for Anselm’s argument.

In (6) & (7) Anselm commits a fallacy of equivocation by treating existence as a predicate or feature of a thing. This reasoning was famously confuted by the 18th century philosopher Immanuel Kant in one of his most popular works the Critique of Pure Reason. Kant argues that existence is not a true predicate or that being is not a real predicate. To gain a better understanding lets refer to Kant’s use of the term true predicates, (logical and real predicates). Logical predicates could be argued as different modes of existence whether real or imaginary. Let us suppose that when reading an epic fairy tail by Alexander Pushkin (1799 – 1837), we imagine his characters existing as an idea in our mind. And, we could also reference Alexander Pushkin (novelist/playwright) who existed at one point in time in Russia during the Romantic era. Both of these subjects though have no real predicates. Alexander Pushkin no longer exists and his fantasy novels have no basis in reality. In such cases existence could be considered a logical predicate or an intrinsic property. But if we grant St. Anselm’s predicate it would be at best a logical predicate but no more real than Pushkin’s fairy tale novels. In linguistics how a subject-predicate works is simple: the subject tells us what (whom) and the predicate tells us something about the subject (Peck, n.d.). Logically this puts Anselm’s argument in a difficult spot. Because the existence of P tells us nothing about the ontology of P and whether P exists as a necessity, possibility, belief, or knowledge. For example: it may be true to refer to ‘Alexander Pushkinas a noun but in what state or capacity would I mean? Without having anything to relate that feature to it just remains an unmodified predicate — a future predicate which remains undetermined.

The ontological argument is an ill attempt at trying to rationalize a metaphysical impossibility. Let us reiterate here that there is no reason to accept (1). The definition of (1) carries no principle ontological bases. Why we should accept (1) leaves the Ontological argument both vulnerable and inoperable. It’s dubious to claim that the ontological argument is a proof by contradiction. The concept of God cannot be inferred from the mind to reality. Because to exist in the mind is not the same as existing in reality; therefore, it is not a true contradiction. For the ontological argument to work one must be able to satisfy it as a synthetic/analytic proposition because ‘existence’ does not contain or modify the concept of God. A predicate must in some form expand upon the subject and demonstrate its modal attitude in whether it exists by necessity, possibility, belief, or knowledge. If the existence of a thing does nothing to modify or change the subject then it is not a true/real predicate. All possible reiterations and interpretations of the ontological argument repeat these same mistakes and fail at convincing even the most devoutly faithful of theologians.

Other Objections

Another of Kant’s objections was to pose the question, “why is existence better than non existence or why is being better than non-being?” If I had an 8oz cup of coffee and not an 8oz cup of coffee the existence or nonexistence of the coffee doesn’t change the predicate. The existence or none existence of something are mutually exclusive events and do not effect each-other. Kant also objects to (1) by stating what is defined as necessary of a thing does not guarantee its existence. If it is necessary for a triangle to have 3 sides that does not mean a triangle exists. Minds do not create things nor bring things into existence by conceiving them.

Gaunilo of Marmoutiers a Benedict monk from the 11th century used a reductio ad absurdum to demonstrate that anything could be proven using Anselm’s reasoning. He uses the example of a Lost Island which no greater can be conceived. Anselm later dismisses this claim as it does not fit the criteria of a necessary being, but his point is trivial. Because the criteria of (1) as a necessary ‘being’ once again implies the conclusion. Put simply Anselm is defining God into existence.

St. Thomas Aquinas, a fellow Catholic monk and patron saint, also objects to the ontological argument by quoting scripture (1 Corinthians 2:9) that no mind can truly conceive of God. St. Aquinas also objects to the misuse of the term ‘existence’ as an equivocation which does nothing to signify that to exist in the mind is to exist in reality.


Himma., E., H., Anselm Ontological Argument for God’s Existence (n.d.). Retrieved from

G., R., Mayes. Logical Consistency and Contradiction (n.d.). Retrieved from

Immanuel., K., Critique of Pure Reason (1781). Penguin Classics (2002). 

Peck., F., Parts of a Sentence – Subject-Predicate University of Ottawa (n.d.). Retrieved from

Peetz., V., Is Existence a Predicate? (1982). Retrieved from

Allen., L., Plantinga’s Ontological Argument (2017). Retrieved from

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