 It is important to emphasize the profound philosophical difference between Prior’s Q and the necessitist’s SQML that is reflected in the preceding observations. As we’ve seen, Q was deeply motivated by Prior’s strict actualism; this is most clearly seen in his introduction of the n-statability operator \(\rS\) and the axioms S1–S3 expressing the necessary ontological dependence of propositions on their subjects. But, in stark contrast to the necessitist’s SQML, Prior’s metaphysical predilections are not baked into Q—unlike the necessitist, he has only made them consistent with his logic; his axioms for \(\rS\) and his distinction between strong and weak necessity only have purchase if \(\textbf{N}_{Q}\) is explicitly denied. For Prior, both necessitism and strict actualism are substantive philosophical theses and, hence, the choice between them—i.e., whether or not to adopt \(\textbf{N}_{Q}\) as a proper axiom of a philosophical theory—is left as a matter for pure metaphysics, not logic, to decide.