Full Idea
There is no reason in principle why the ultimate source of what is true should always lie in what exists.
Gist of Idea
Truths need not always have their source in what exists
Source
Kit Fine (Guide to Ground [2012], 1.03)
Book Reference
'Metaphysical Grounding', ed/tr. Correia,F/Schnieder,B [CUP 2012], p.44
A Reaction
This seems to be the weak point of the truthmaker theory, since truths about non-existence are immediately in trouble. Saying reality makes things true is one thing, but picking out a specific bit of it for each truth is not so easy.
Related Idea
Idea 18877 Moral realism doesn't seem to entail the existence of any things [Cameron]