The second 'broad assumption' (¬p ∧ ¬Fp) → P¬Fp is not true when p refers to a future contingency

So the Master Argument is indeed valid. The fallacy, Prior tells us, lies with the second ‘broad assumption’ \((\neg p \amp \neg Fp) \rightarrow P\neg Fp\) (which says: when anything neither is nor will be the case, it has been the case that it will not be the case). This, Prior tells us, is not true if \(p\) refers to a future contingency, and thus has the truth value ½ or ‘indeterminate’. Where \(p\) is indeterminate, both \(Fp\) and \(\neg Fp\) are indeterminate, so the consequent of the disp