 However, from a philosophical point of view it has been debated whether or not the ontological import of his third grade tense logic is the same as the ontological import of the first-order earlier-later logic. For example, the \(\mathtt{\forall}\) binder is by some authors considered a direct analogy to the first-order \(\mathtt{\forall}\) quantifier, and therefore suspect; see for example the paper Sylvan (1996) in the collection Copeland (1996). See Braüner (2002) for a discussion of Prior’s fourth grade tense logic. See also Øhrstrøm and Hasle (1993), Øhrstrøm and Hasle (2006), Müller (2007), and Blackburn (2006). Finally, see the discussion of Prior’s four grades in Chapter 1 of Braüner (2011a).