 There appear to be two broad kinds of justification for subjunctive conditionals, which are logical and ontological, where logical justifications are derived from the grammar and vocabulary of a specific language, such as English. The subjunctive, “If John were a bachelor, then John would be unmarried”, for example, follows from the definition of “bachelor” as “unmarried, adult male”. Analogously, the subjunctive, “If this were gold, then it would be malleable”, could be justified on ontological grounds if being malleable were (let us call it) a permanent attribute of being gold as a reference property, where attributes are “permanent” when there is no process or procedure, natural or contrived, by means of which things having those reference properties could lose those attributes except by no longer possessing those reference properties, even though that is not a logical consequence of their respective definitions (Fetzer 1977). The approach appeals to necessary connections, which are unobservable and therefore unacceptable to Hume. As we shall discover, that they are unobservable doesn’t mean they are empirically untestable.