ABSTRACT: For the Stoics, a syllogism is a formally valid argument; the primary function of their syllogistic is to establish such formal validity. Stoic syllogistic is a system of formal logic that relies on two types of argumental rules: (i) 5 rules (the accounts of the indemonstrables) which determine whether any given argument is an indemonstrable argument, i.e. an elementary syllogism the validity of which is not in need of further demonstration; (ii) one unary and three binary argumental rules which (...) establish the formal validity of non-indemonstrable arguments by analysing them in one or more steps into one or more indemonstrable arguments (cut type rules and antilogism). The function of these rules is to reduce given non-indemonstrable arguments to indemonstrable syllogisms. Moreover, the Stoic method of deduction differs from standard modern ones in that the direction is reversed (similar to tableau methods). The Stoic system may hence be called an argumental reductive system of deduction. In this paper, a reconstruction of this system of logic is presented, and similarities to relevance logic are pointed out. (shrink)

A-LOGIC is a full-length book (600+ pg). It functions as a system of logic designed to: 1) solve the standard paradoxes and major problems of standard mathematical logic; 2) minimize that logic's anomalies with respect to ordinary language, yet; 3) prove that all theorems in mathematical logic are tautologies. It covers lst order logic the logic of the words "and", "or", "not", "all" and "some". But it also has a non truth functional "if...then" and differs in its definition of validity, (...) its semantics and its theorems. In the book A-logic is contrasted step by step with standard mathematical logic as presented and defended by Quine. All of standard logic's theorems are proven tautologies in A-logic. But some argument-forms called "valid" in standard logic are not valid in A-logic -- notably non-sequiturs like "(P and not-P), therefore Q". In addition A-logic has many tautologies with its non-truthfunctional "if ... then" that standard logic can not derive -- e.g., "Not-(if P&Q then not-P)." A-logic's semantics is based on syntactically defined concepts of logical synonymy and containment of meanings rather than on truth-values and truth-functions. Its "if...then" sentences (called "C-conditionals") are valid if and only if (i) the meaning of the consequent is logically contained in that of the antecedent, and (ii) the antecedent and consequent are jointly consistent. The predicate "valid" holds only of C-conditionals and arguments. No valid C-conditionals are translatable into standard logic though all of them imply tautologies of standard logic. (shrink)

"Attempts to unite the fields of mathematical logic and general algebra. Presents a collection of refereed papers inspired by the International Conference on Logic and Algebra held in Siena, Italy, in honor of the late Italian mathematician Roberto Magari, a leading force in the blossoming of research in mathematical logic in Italy since the 1960s.".

Stoicism is one of the richest and most influential intellectual traditions of antiquity. Leading scholars here contribute new studies of a set of topics which are the focus of current research in this area. They combine careful analytical attention to the original texts with historical sensitivity and philosophical acuity, to provide the basis for a better understanding of Stoic ethics, political theory, logic, and physics.