Is "anything truly possible"?
Well, everything that actually exists would seem to therefore be possible.
So I take it that the subject line should read: "Is everything truly possible"?
Some people (including me) would say that "Everything possible is possible", but that's a tautology and not very informative.
But I'm inclined to think that some things aren't possible, at least in this universe, governed as it is by logic.
So, should a state of affairs that isn't possible even be included in the scope of 'everything'? What does 'everything' mean here? Every linguistic expression that supposedly refers? Everything conceivable? Everything possible? What universe of discourse is 'everything' ranging over?
Not to me , but many others might think , give an example of otherwise .
A mountain is not made of water . Grass is not concrete etc .
Water is thought to have properties inconsistent with what's observed to be the substance of mountains. So the logic problem might be applicable there.
Except... that in the outer Solar System, water ice functions as rock and there are indeed mountains of solid water. (And on very hot exoplanets that orbit very close to their stars, the silicates that form most of our Earthly rocks might be liquid or even gas.) It's all relative.
But that being said, we still might want to say that something can't simultaneously be A and not be A.
But on the other hand, A still might be ~A in different respects or at different times.
Therefore is " anything is possible " a true statement ?
I'm inclined to say 'no', but it's a more complicated issue than it might at first seem. So I don't really know the answer. It's another of the mysteries.
It raises all sorts of very technical difficulties in the theory of reference, modal logic and metaphysics.
https://www.iep.utm.edu/mod-meta/
https://www.iep.utm.edu/mod-illu/