 We say that a formula of OBTL is Ockhamist valid iff it is true at all instant-history pairs in all Ockhamist tree models. Obviously, all temporal formulae that are valid in linear models of time are Ockhamist valid as well. Hence, Ockhamism validates the principle of future excluded middle \(F\varphi \vee F \neg\varphi\) (under the assumption that time does not end) as well as the formula \(\varphi \rightarrow HF\varphi\). It invalidates, however, the principle of the necessity of the past \(P\varphi \rightarrow \Box P\varphi\), and it thereby blocks Diodorus’ Master Argument. 