This is odd:
"Everything exists. Trees exist. Rocks exist. Unicorns exist. Minds exist. Dreams exist. Atheists exist. God exists. Hallucinations exist. A term that is predicable of everything, however means nothing. ...[E]xistence is indistinguishable from nothing." - John Robbins, Without a Prayer: Ayn Rand and the Close of Her System, 1997, p.87
"Being and reality are so universal as to be meaningless. A word that is applicable to everything is applicable to nothing. if trees exist and are real, so do dreams exist and are real. Hallucinations are real hallucinations" - G.H. Clark, The Philosophy of Gordon H. Clark, 410
If you were to ask either of them, "How does a unicorn exist, I thought they didn't?", they would reply, "No, they do exist, they exist as concepts in your mind."
Well, not quite so fast.
Isn't there a distinction between a unicorn existing and a concept of a unicorn existing? Those are not the same claims, the same proposition.
In fact, a unicorn is a winged horse with a single horn protruding out of the head.
Now, to say that "A unicorn does not exist" is to say "there is no thing that is a horse and instantiates the property of being winged and horned.
My concept of a unicorn does not instantiate the properties wingedness and hornedness.
So, it seems plainly false to me that "unicorns exist." A concept, drawing, or image of a unicorn may certainly exist, but that is not the same thing as saying that a unicorn exists.
If they're right, the good news is that fairies, like Tink, will not have to worry about dropping dead. Fairies are "real," they "exist." Remember when Pan said,
"Every time a child says, 'I don't believe in fairies,' there is a fairy somewhere that falls down dead."?
And how did they bring Tink back?
"She's going to die unless we do something. Clap your hands! Clap your hands and say, 'I believe in fairies!'" [The children shout] "I do believe in fairies, I do! I do! I do believe in fairies, I do! I do!"
And so at best, Clark and Robbins have found a way to keep the fairy population from shrinking.