Document Type : Research Paper


Associate Professor of Dept. of Philosophy, Tarbiat Modares University


According to Muslim logicians, the quantifier, in categorical logic, shows the quantity of the individuals of the subject in a statement; so its place is before the subject. Hence, if it comes before the predicate there arises some deviation in the main form of the statement, and such a statement is called a "deviant statement" (al-qaḍiyah al-munḥarifah). In modern logic, by contrast, the main characteristic of a predicate is being general or unsaturated and since a predicate has a propositional function, i.e. has free variables (or arguments), it can or should be quantified; hence, putting the quantifier before the predicate is consistent with the conditions and rules on constructing a well formed statement. Among contemporary logicians Hamilton is famous for his claim that predicates should also be quantified just like subjects. The viewpoints of Muslim and modern logicians, concerning the place of the quantifier in a statement, seems to be conflicted. Among Muslim logicians, Avicenna is the one who considers no problem in using such statements, although he calls them “deviant”, and gives an explanation and analysis for them. In this paper, I have examined these views and shown that the conflict may be superfluous if Muslim logicians’ approach to predicates is extensional, which, of course, can hardly be attributed to them.


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