Philosophy Stack Exchange is a question and answer site for those interested in the study of the fundamental nature of knowledge, reality, and existence. It only takes a minute to sign up.
Sign up to join this community
If "an apple doesn't exist" means "not only an apple doesn't exist in reality, but also an apple doesn't exist in mind or anywhere",
Is an apple, which doesn't exist, not an apple or is an apple, which doesn't exist, still an apple?
Why I'm confused is this:
I consider a misuse of language to be the source of confusion:
Of course we can form the word “apple” in our mind. It is a concept invented to denote certains objects, like so many other concepts do. But “A non-existent apple” is a term which has no reference.
Example 1: Assume that on the table there is no apple at all. Speaking about the “non-existent apple on the table” is at risk to misuse the language. Better to transform the statement into “There is no apple on the table”. After the transformation everybody understands that the attribute “non-existent” means a negation like “there is no apple …“
Example 2: If there is only a green apple on the table. It is risky to speak about “the non-existent red apple on the table". Better to say “There is no red apple on the table”.
In both cases, after the linguistic transformation nobody will ask about properties of non-existent apples and run into a confusion.
The idea to transform statements about the property of non-existent things to the form “there is no thing with the property …” is due to Bertrand Russell with his example “the king of France is bald”, spoken at a time when there was no king of France, see his essay.
It rather depends on how you choose to use the terminology, particularly the word 'exists'. Also, on whether your preferred approach to ontology includes non-existent things.
Since the time of Frege and Russell, it has become common to treat existence as the property of a concept, rather than the property of an object. On this approach, to say, "there exists an apple" does not assert that some thing - an apple thing - has the property of existing, but rather that the concept apple has at least one instance.
This approach is consonant with Kant's argument that existence is not a property of things. It has the merit of avoiding apparently nonsensical talk of non-existent objects and what properties they might or might not have. In formal logic, it takes the form of representing existence using quantifiers rather than using predicates, and of requiring that names always have a referent.
But this approach does face some issues. How do we state that some particular thing does not exist? How do we talk about things with potential existence? Things that might have existed but actually do not? Things that are fictional, or imaginary, or hypothetical? Before Russell, Meinong proposed an ontology in which such things are permitted to be the object of logical discourse, but they do not exist in the same way that real things exist. They may be said to subsist, or to be part of an extended domain of things that includes possible things that are not real.
On Meinong's approach, a non-existent apple may subsist without having actual existence, and it may have properties such as being green or red. Also, there may be concepts that have no real instances, but which may have subsisting instances. On this view, a statement like "dragons breathe fire" is neither trivially true nor trivially false, just because there are no real dragons. (Though it is problematic to say just what are the truth conditions of "dragons breathe fire".)
Russell's approach to logic was a reaction against Meinong, and it has dominated and continues to be mainstream. But philosophers enjoy pushing on the boundaries of logic and they have found ways to talk about non-existent objects. One way to do this is to talk of possible worlds and of objects that exist in some possible world, but not the actual world. Another is to treat potential existence along the lines of the Meinongian category of subsistence. In formal logic, this approach may take the form of using free logic, which refers to logics that permit domains of things that do not exist, and names that have no referent.
