Do you think Plantinga's claim that Anselm does not use existence as a predicate/attribute in his proof is consistent? I don't think it's quite right. Because Plantinga himself states that Anselm uses existence as one of the great-making properties. According to Anselm's proof, when we consider two entities A and B, if all the attributes of entities A and B are equal and A exists but B does not, then entity A is greater than entity B. In this case, obviously being is accepted as a predicate/attribute. Anselm did not define God by specifying attributes for God and adding existence to them, but he clearly accepted existence as a quality. When we think from this point of view, Kant's criticisms will also be related to Anselm's proof. Up to this point, Kant's critiques also target Anselm's proof, and Plantinga's claim that Kant's critique is not relevant to Anselm's proof seems unsatisfactory.

Can I get your thoughts on this subject too?

  • Even assuming that Anselm did think of existence as a predicate the only relevant issue is whether he used that in constructing his argument. And (on Plantinga's definitional interpretation of what "existence is not a predicate" means) he did not. We do not have to accept the premise "existence in reality is greater than existence in the understanding alone" on the basis of adding existence to someone's list of attributes. Existence can make something greater, after all, whatever its status is, predicate or not.
    – Conifold
    Aug 7, 2021 at 14:36
  • I wasn't able to find a precise statement of Plantinga's response to Kant, but I was able to find this discussion of Plantinga's own ontological argument in SEP. SEP is pretty harshly critical of it.
    – Kevin
    Aug 7, 2021 at 19:07
  • 1
    @Kevin The OP refers to Plantinga's paper that discusses Anselm's original argument and Kant's objection. Plantinga's own modal argument is a different topic.
    – Conifold
    Aug 8, 2021 at 21:40

2 Answers 2


The basic problem here is that Plantinga claims to understand what Anselm was talking about in the first place. SEP describes no less than five different formulations of Anselm's argument which have been suggested by various commentators, criticizes all five interpretations on various grounds, and then suggests that Anselm may in fact have made an elementary logical error (thus putting forward a sixth interpretation). While it is possible that Plantinga's interpretation of Anselm happens to match what Anselm intended, it strikes me as rather unlikely given the diversity of opinion which the text has produced.

If we set that problem aside, the next problem is with this line in (Plantinga's interpretation of) Anselm's argument:

(2) Existence in reality is greater than existence in the understanding alone. (premise)

Plantinga writes that:

If this is what [Kant] means, he's certainly right. But is it relevant to the ontological argument? Couldn't Anselm thank Kant for this interesting point and proceed merrily on his way? Where did he try to define God into being by adding existence to a list of properties that defined some concept? According to the great German philosopher and pessimist Arthur Schopenhauer, the ontological argument arises when "someone excogitates a conception, composed out of all sorts of predicates, among which, however, he takes care to include the predicate actuality or existence, either openly or wrapped up for decency's sake in some other predicate, such as perfection, immensity, or something of the kind." If this were Anselm's procedure -- if he had simply added existence to a concept that has application contingently if at all -- then indeed his argument would be subject to the Kantian criticism. But he didn't, and it isn't.

Unfortunately, at this point Plantinga turns away from Kant and proceeds to "take an independent look at" the ontological argument, so we don't get any further elaboration on why (2) does not constitute exactly what Plantinga is describing.

Maybe Plantinga meant something like this: Anselm is not adding existence to God's set of predicates, he is merely arguing that "existence in the understanding alone" is "less great" than "existence in reality" - i.e. that an object which "exists in the understanding alone" is necessarily less great than an object which "exists in reality." Plantinga then goes on to examine what it means for an object to "exist in the understanding alone," eventually concluding that we may speak of such "possible objects" as a shorthand for a set of predicates which may or may not be instantiated in a given possible world. For example, the claim that "Black swans could possibly exist" is reformulated as the claim that "In at least one possible world, there is an object which is a black swan." Thus, his interpretation of Anselm is formulated in terms of modal logic and Kripke semantics (which, IMHO, doesn't really sound a lot like what Anselm actually wrote). This sidesteps Kant's objection to "non-existent objects" and existence-as-a-predicate. However, in the context of the rest of Plantinga's discussion of "greatness" and "excellence," it also makes the assertion that "God's existence in reality is conceivable" a great deal stronger than it might appear, to the point that the atheist can reasonably reject this premise as unfounded or at least not self-evident.


First of all, as Plantinga stated, it seems quite reasonable to think that determining whether a concept refers to an entity or not, by going beyond the concept in question, is more valid for possible (contingent) entities. Because, in ontological proof, first starting with a concept whose equivalent and equivalents (reality) are possible, then an existence is not attributed to this concept. Therefore, Kant's objection does not refute the absence of necessary propositions with ontology, nor does it show that the proposition "God exists" is not a necessary truth. The point that Plantinga rightly underlines here is the thought that determining whether the concept of "necessary being", which is unique to God and unique to God, does not require going beyond that concept, which is the intuition that forms the basis of ontological proof.

By the way, Kant examined the concept of being superficially with a general point of view. Being may be a prerequisite for having certain qualities in general. However, Kant ignored the decisive role of being in some situations, such as necessarily existing or contingent, existing in the mind or existing in reality. The claim that existence is not a predicate is not a tangible answer to the logic of the ontological argument, that it is contradictory to consider the absence of anything greater than itself.

  • This argument - like Platinga himself - seems to be ignorant of the context and precise wording, and thus totally misses Kant's point in the first place.
    – Philip Klöcking
    Aug 11, 2021 at 16:29

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