 These observations may well have distracted many non-classical logicians from connexive logic at that time. If the validity of Aristotle’s and Boethius’ Theses is distinctive of connexive logics, it is, however, not quite clear how damaging the above criticism is. In order to construct a more satisfactory system of connexive logic, McCall (1975) defined the notions of a connexive algebra and a connexive model and presented an axiom system CFL that is characterized by the class of all connexive models. In the language of CFL, however, every implication is first-degree, i.e., no nesting of → is permitted. McCall refers to a result by R. Meyer showing that the valid implications of CFL form a subset of the set of valid material equivalences and briefly discusses giving up the syntactic restriction to first-degree implication. Meyer (1977) showed that the first-degree fragment of the normal modal logic S5 (and in fact every normal modal logic between KT and S5, cf. the entry  logic: modal)  and CFL are equivalent in the following sense: all theorems of CFL are provable in S5 if the connexive implication A → B is defined as □(A ⊃ B) ∧ (A ≡ B), where ⊃ and ≡ are classical implication and equivalence, respectively, and every first-degree theorem of S5 is provable in CFL if □A (“it is necessary that A”) is defined as (~p ∨ p)→A. In summary, it seems fair to say that as the result of the investigations into connexive logic in the 1960s and 1970s, connexive logic, its ancient roots notwithstanding, appeared as a sort of exotic branch of non-classical logic.