Abstract

The main doctrines of the traditional logic of terms (logica termini) are standardly organized according to the formation structure of syllogistic inferences. A syllogistic inference is analyzed into propositions, and propositions, in the last instance, to terms; the logic of terms, in line with this formation structure, is partitioned into the doctrines, respectively, of terms (terminorum), of propositions (propositionum) or judgments (judiciorum), and of immediate and mediate inferences or followings (consequentiarum immediatarum/mediatarum). This structure communicates the idea that a given doctrine could be treated, to a certain extent, independently of the next one to come, so that propositions, for instance, could be examined, at least to a certain extent, independently of syllogistic inferences. Some classical philosophers such as Immanuel Kant have developed approaches that break in part this order of analysis which finds its clearest expression in the Port-Royal logic (Arnauld & Nicole’s Logic or the Art of Thinking). In Kant’s case the order is changed in favor of the doctrine of judgements. This paper examines the French philosopher Jules Lachelier’s (1832-1918) approach which similarly breaks the same doctrinal order, and which, more specifically, refines the typification of propositions according to the roles to be played by propositions in syllogisms. What lies at the core of this approach is the identification of the semantic values of categorical propositions (or, as Lachelier calls them, of propositions of inherence) in terms of modal statuses which are to determine these roles. Lachelier seems to use the set of values he assigns to the categorical forms as a tool for testing logical implication among types of predication, that is, as some sort of semantic theory in the modern sense. Lachelier also discusses the three-figured categorical syllogistic along with a method, effectively used by G. W. Leibniz, of transforming syllogistic moods into each other, and tries to confirm his semantic theory in terms of such syllogistic. This paper explains Lachelier’s analysis of meaning by treating it as a non-formal semantics of predication, and tries to make some modern sense of Lachelier’s general approach to syllogistic.