عنوان مقاله [English]
The habit of using well - established terms in traditional debates of a science makes people to have this attitude that also in daily and current discussions of that science these terms are always used with the same meaning. This opinion in many cases brings about error and mental perversions. Among the sciences in which the possibility of such a problem seriously exists is science of logic. Description and analysis of conditional propositions in Ibn Sina's logic and his followers shows these points. First, although non – predicative propositions have been designated as "conditional propositions" but habitual and literal concept of condition has no any necessity and certainty in the realization of this kind of propositions. Secondly, common criterion of being conditional among conjunctive and disjunctive propositions is indicative of a conviction to the possibility in the kinds of this division in Avicennian logic. With these two foundations, the scope of the extent of conditional propositions can cover all kinds of compound propositions in modern logic. Such an extent can be regarded as a good ground for this proposal: the term "conditional" in the subject of Avicennian logical propositions can be considered as an equivalent of the term "compound" in discussion of compound proposition in modern logic.