Gödelian incompleteness and the principle of falsifiability advanced by KarlPopper together necessitate that outside of a formal system of limited application, a "truth", to have any measure of rational support, must by necessity, always be provisional, incomplete and falsifiable, in other words, there must always, at least hypothetically, exist some evidence which would permit that supposed truth to be rejected. This implies that outside of formal systems, the truth of a thing is not an absolute, but encompasses a range of probabilities which will have varying truth values (i.e. from "false" through "insufficient evidence to adduce a truth value" to "true") depending on the evidence for or against such a thing.
See also: acceptance, belief, faith, trust, truth value