قياس مساوات و منطق نسب

Equivalence Syllogism and the logic of Relations

Muslim ligicians faced with problems in justifying certain simple reasonings (Such as equivalence syllogism) and these problems; were rooted in their commitment to categorical syllogism. In this regard weakness of early logic has nothing to do with relation as such that is, it is not such that early logic was unable to prove those reasoning which containd relation due to possesing relation. On the contrary, their main problem was that they relied on the analyses of propositions in terms of subject and predicate and focusing their attention to categorical syllogism. That is, in any reasoning subject predicate and middle term should be ascertained and evidently such process is not possible every where. Therefore, equivallence syllogism reveals a defect in Aristotelian system of subject predicate - relation. For, on the one hand, Aristotelian version of syllogism requires that the premises of syllogism should be analysed into terms and each term in modern logic term is a single positional predicate. While equivalence syllogism is formed of certain premises that involve relation or categorical section of multi - position predicates. Hence refereing equivalence syllogism to the conjugate syllogism is not devoid of objection.