What is the difference between “unicorns don’t exist” and “unicorns don't really exist”? Is this similar to how "it is true that there are unicorns" reduces to "there are unicorns"? Or is it more like the following discussion in the Stanford Encyclopedia of Philosophy article on actualism?

The possibilist's thesis, however, is that existence, or actuality, encompasses only a subset of the things that, in the broadest sense, are. Rather, in addition to things like us that actually exist, there are merely possible things — possible Aliens, for example — that could have existed, but, as it happens, do not. So there are such things, but they just happen to exhibit a rather less robust but nonetheless fully-fledged type of being than we do.

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    I realize that the question seems simple enough to introduce without much preamble or commentary, but we do prefer longer questions. At any rate, see here for a relevant analysis. Jul 2, 2021 at 12:30
  • Quite different. It's the existence of an object within an assumed context (reality) vs. the non-existence of the same object. Unicorns DO exist in fairy tales, which is enough for our reason to accept some existence, and DON'T exist (AFAWK) in our reality.
    – RodolfoAP
    Jul 2, 2021 at 12:45
  • @RodolfoAP “Unicorns don’t exist” can mean unicorns don’t exist physically, mentally and even spiritually? Jul 2, 2021 at 12:52
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    Please, explain the meaning of "unreally exist” Jul 2, 2021 at 13:05
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    First of all, you have to decide the way to use "existence": is it "physical" existence (space-time location, etc.) ? or does it mean "to be conceivable" (Intentional object)? Jul 2, 2021 at 13:09

1 Answer 1


It is only a question of how you wish to use the term "exist." It's just a word, it can be used any way you like.

  • You may use the word "exist" (or "real") to refer only to physically existent things in our current physical universe, such as hamburgers but not unicorns.
  • You may use these words to refer to things that could conceivably exist, even if physically they do not exist in this universe.

In your quote about the "possibilist's thesis," the "possibilist" uses the word "are" (as in "there are") to refer to things that might not physically exist, as long as it is conceivable for them to exist. He uses the word "exist" to refer to things that physically exist in this universe.

There is not a clear consensus on how to use these words, but here's what I'd suggest:

  • Usually, use "exist" in the strict sense, to talk about what physically exists in this universe.
  • When speaking of mathematical objects, we may use the word "exists" in a conceptual sense, but it should be understood that this is a different sense than the sense in which objects exist physically. It might as well be a different word.
  • When speaking of fictional objects, we may also use "exists" in a conceptual sense. If we are asked whether they "really exist," there are two answers: within Superman's fictional universe, yes, Superman "exists" and "really exists." Within our universe he neither "exists" nor "really exists." It simply depends on whether you are using the "physically real" or the "conceivable" sense of the word "exists," which depends on the context.

So, to sum up, my suggestion would be to use "exists" by default in reference only to physical existence in this universe, but to switch to other senses of the word as clear from context, without forgetting that they are different senses.

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