 Prior himself did not accept the view represented in the Ockhamist system, but as many later researchers he was interested in the exploration of the system. It should be mentioned that the basic views held by Belnap et al. (2001) are in fact rather close to Priorean Ockhamism, although there are certainly many further developments of the theory in Belnap’s philosophical writings on the subject (Belnap 1992, 2002, 2003, 2005). Belnap has strongly emphasized the distinction between what he calls ‘plain truth’ and “settled truth”. Whereas plain truth corresponds to the branch-dependent truth used in the Ockhamistic model, settled truth will be branch-independent, i.e., truth at a moment of time. It should also be pointed out that in the definition of \(Ock\), only (d) differs from the corresponding Peircean definition. In fact, Prior (1967, p.130) has pointed out that the Peircean system may be seen as a fragment of the Ockhamistic system in which \(F\) does not occur except as immediately preceded by an necessity operator.