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 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 at 5:25

1 Answer 1


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.

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