 Whereas in the Peircean branching time logic PBTL future truth is modalized, in the Ockhamist branching time logic OBTL future truth and modality come apart. The Peircean formulae \(F\varphi\) and \(G\varphi\) are equivalent to the Ockhamist \(\Box F\varphi\) and \(\Box G\varphi\), respectively. In fact, PBTL can be regarded as a proper fragment of OBTL, namely the fragment that comprises all and only those formulae that are recursively built up from (instant-based) atomic propositions using truth-functional connectives and the combined modalities \(\Box F\), \(\Box G\), and their duals \(\Diamond F\) and \(\Diamond G\). However, the Peircean language is less expressive than the Ockhamist one, lacking e.g. an equivalent for \(\Diamond GF\varphi\) (for a proof, see Reynolds 2002).