Abstract

Like the other logical issues, this issue also has been introduced by Aristotle. Unlike the Muslim thinkers, who classified the modals under three groups, he classifies them under four groups, as follows:1- Necessary, 2- Impossible, 3- Likely, 4- Possible.In some places, Arostotle's expressions are not clear at all, and so scholars have provided various interpretations of it. Some believe that in the book Pere Hermeneias, Aristotle has made no distinction between possible and likely; and he has employed the two as synonyms.About the three fold modals, logicians, theologians, and philosophers discuss in their own books; and so a question arises: is there any discrepancy between logical, theological, and philosophical discussions?Concerning this issue, there are two points of view, as follows:1- Concerning the issue of three fold modals, there is no conceptual discrepancy between logic, theology, and philosophy; they are different only in use and referents. That is, the same definition, posed in logic for the necessity, possibility and impossibility are introduced in theology and philosophy; the logician, however, deals with the proposition or copulative existence, since it is an intelligible issue; theologian or philosopher, however, pays no attention to proposition or copulative existence between predicate and subject; but he deals with the predicative existence.2- In addition to the difference in use and referents, the issue of three fold modals is conceptually different in logic, philosophy, and theology. That is, in the philosophy and theology, one assigns a proper predicate to the subject, necessarily, possibly or impossibly; thus by the necessity, possibility and impossibility, respectively, the Necessary Being, possible being, and impossible being are meant. In logic, however, since the predicate is more general than existence and non-existence, so by the necessity, the necessity of predicate in relation with the subject is meant, and by the possibility or impossibility, possible or impossible beings are not meant, but possibility or impossibility of assigning the predicate to the subject is intended.