 The unprovability of \(\rS \tau\) in Q and, hence, more generally, Q’s inability to prove the existence of any necessary beings is the key difference between Q and SQML and, more specifically, it is what justifies the inapplicability of the full necessitation principle Nec to formulas containing free terms, since some of those terms might refer to contingent beings. This is, in particular, the key to blocking the controversial theorems of SQML, as their proofs all depend essentially on such an application of  Nec.[80]  Indeed, Q is essentially just SQML shorn of its necessitism. If, as Prior (1967: 155) observed, we restore it by ruling out the prospect of contingent beings explicitly,