 Prior’s basic tense logic TL is neutral about the structure of time. In a branching time setting with alternative future possibilities, the original semantics of the future operator \(F\) is, however, no longer adequate to capture future truth. In such a setting, the future operator \(F\) merely reads “it will possibly be the case that \(\dots\)”. Prior (1967, Chapter 7) therefore considered two alternative semantics for the future operator in branching time, which give rise to the Peircean and Ockhamist branching time temporal logics, respectively.