If existence is not a property then doesn't it follow that necessary existence is also not a property? If it is then why?

  • According to Kant, neither possible existence nor necessary existence are substantive properties (material predicates) anymore than actual existence is. But sometimes we think that if a being is necessary, this is "explained" via things like, "This being has the power to resist being negated by any being, itself or any other," etc. so being necessarily existent would seem to require having special properties nevertheless. Nov 9, 2023 at 16:41
  • Within alethic modal logic you can employ free logic with Existence predicate to felicitously express your 'necessary existence' property for either a rigid or non-rigid denoting term as colloquially understood. If you don't believe existence could be a property following Kant, then of course necessary existence is neither a property but modality of some existential truth token or Σ type... Nov 10, 2023 at 5:25
  • I recall reading Kant was of the view that to say "god is blue" means "god (exists and) is blue". To argue that "god is blue" and therefore (??) "god exists" is then a circulos in probando. Kant simply left it as, "exists" adds nothing to god in the statement "a blue god exists".
    – Hudjefa
    Dec 10, 2023 at 23:31

3 Answers 3


If necessary existence means being quantified over in every possible world, and quantification is not substantively predicative in the required manner, then necessary existence is not a property as such anymore than being quantified over in merely one world would be. This is somewhat murky, though, insofar as we might not wish to locate certain necessary beings within individual possible worlds, but we might wish to locate them in some sort of hyper-world encompassing or simply beyond the ones we usually deal with.

The question becomes somewhat murkier once we go on to imagine nontrivial iteratability for possibility and necessity (see e.g. Gregory[11] or Betz[09]): if necessary existence is, or is not, a substantive property, what about necessarily necessary existence, necessarily necessary necessary existence, etc.? One almost feels like the more such iterations were to be carried out without collapsing into a single modal prefix, the more one might approach a substantive modal property. But then eventually we will need a sharper theory of properties generally-speaking, of qualitative and non-qualitative properties, etc. Kant would say something like this: visualizing a rock and visualizing a necessarily existent rock are no different as mere visualizations, so there is some lack of descriptive "content" involved in modal attributions. But meaning, content, truth-aptitude, etc., can come apart variously, so we would want to distinguish between saying that modal attributions add no content to a concept, and saying that they add no meaning or do not affect truth-value. They clearly enough affect truth-value, after all, and have some meaning (some use/function).

Selected further reading (from the SEP):

  1. Rigid Designators
  2. Category Mistakes: Semantic Approaches
  3. Hyperintensionality
  4. Transworld Identity
  5. Haecceitism
  6. The Possibilism-Actualism Debate
  7. Nonconceptual Mental Content
  8. Concepts
  9. Properties

If it is then why?

My dog exists.

The Unicorn doesn't.

So, existence is a property of my dog, but it is not of the Unicorn.

doesn't it follow that necessary existence is also not a property?

The only necessity is logical necessity: To say that ψ → ξ is true is to say that if ψ is true, then ξ is true.

That is to say, ξ is necessarily true when ψ is true.

Which is why we say that ξ is the necessary condition of the implication ψ → ξ.

Existence is necessary if the existence of y follows from some assumption. For example:

Horses exist and they are mammals, therefore mammals exist

Once you recognise that horses exist and that they are mammals, you have to recognise that necessarily mammals exist. The existence of mammals is necessary if horses exist and are mammals.


You would be correct, OP, if necessary is a subset of (existence is a subset of nonproperties).

However, if that's not true ...

P. S. Someone should ask the mods to activate LaTex on Philosophy SE.

  • 1
    The best workaround for the lack of LaTeX here is to do the text up in a word processor (or over on one of the SEs that supports the formatting), screenshot the do-up, crop it, then add it here as an image. Still clunky but it looks nice enough :) Dec 11, 2023 at 0:09
  • @KristianBerry, it doesn't make sense for a philosophy forum not have LaTex enabled, since that's necessary for symbolic logic and every schoolboy knows logic is a subdiscipline of philosophy. QED ■
    – Hudjefa
    Dec 11, 2023 at 1:49
  • I more or less agree, but I don't know what makes updating this SE prohibitive in this regard. I think we have issues with migrating posts to or from various SEs, too, which issues escape me also... Dec 11, 2023 at 2:31
  • @KristianBerry, sequere pecuniam? How many hits does this subforum get? The Math SE is literally a frenzy of activity, it's LaTex enabled.
    – Hudjefa
    Dec 11, 2023 at 5:11

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