مجله معارف منطقی
پیاپی 12 (بهار و تابستان 1399)

Dividing propositions into factual and actual is one of the innovations of Muslim logicians. At a point in the history of logic, this division was denied by some of the great logicians. The origin of this denial was an interpretation of factual propositions presented by Mohaghegh Tusi who attributed the denial of factual propositions to Ibn Sina. By examining the definitions of factual propositions and tracing the first contexts of this division, especially in Farabi's works, the present paper proves that one can provide some other interpretations and definitions of factual propositions that not only are compatible with the principles and foundations of logic and have better logical and epistemological bases, but also are consistent with the principles of Ibn Sina. Based on the preferred definition and interpretation of factual propositions, this type of proposition is comparable with a variety of propositions in Islamic epistemological issues such as secondary premises (the intuitive cognitions and sensations), in Western philosophy with subjects such as the relation of things in Hume's philosophy, real facts (factual) in Leibniz’s philosophy and composite propositions in Kant’s philosophy. According to the preferred interpretation, in terms of the source of truth and the amount of validity in epistemology, factual propositions have special rulings that are discussed in this paper.

Opposition in single words includes contradiction, contrast, absence, possession and correlative. Opposites are divided into four types: contradictories, two opposites, absence, possession and two correlatives. The subject of this research is to examine the truth of the opposition of contrast and two opposites. Contrast exists both in propositions and in singular concepts. This paper discusses the latter, which is referred to as contrast in issues and contrast in entities. It is argued that, like other types of the opposition of singular concepts, contradiction in singular words is one of the rules of factual existence and is considered a philosophical issue. To explain the truth of two opposites, the definitions of two opposites and the differences between these definitions must be examined. The existentiality of two opposites, commonalties of the same genus, ultimate contradiction in two opposites, the necessity of subject or its importance for two opposites, the succession of two opposites, individuality or universality of the subject of two opposites, the essentiality of the impossibility of bringing them together are among the important dimensions of differences in definitions of two opposites. Through investigation of these dimensions, two real opposites are distinguished from commonly accepted ones, and also two intrinsic opposites are differentiated from two opposites by accident. By examining the definitions of two opposites, the nature of contrast and the divisions of two opposites become clear.

Verbal signification has different divisions. According to the preferred view, these categories can be included in a comprehensive system or categorized in a comprehensive division. Now a difficult question that we are faced with is: what is the relationship between prerequisites and signification? Basically, is there a relationship between them? If yes, how is this relationship manifested? Can the implication by association be interpreted as necessity in terms of prerequisites? To get a proper answer, we must look at the quiddity of prerequisites and its types and explore this issue in Osul and logic. In this study, in addition to achieving the most important and special rational rules that govern the field of signification, two other scientific achievements were made; first, in the area of signification, there should be a distinction between single words and sentences and overgeneralization of a divisive rule to other divisions should be avoided. Second, signification should not be interpreted as clear signification which is discussed in the area of prerequisites.

As the second prophet living among the worshippers of idols and celestial bodies, Prophet Abraham explained the important principle of monotheism. He used argument, dialectics and preaching in his argumentations. What is noteworthy in his argumentations is the avoidance of irrational words and the use of logical methods that call for monotheism only through knowledge, insight and certainty, not on the basis of fantasies, superstitions, false implications and impractical promises. Therefore, the use of argument in the Prophet's argumentation method has been taken into account. Using librarybased method and through reviewing the verses of the Holy Qur’an, this research has answered the question as to how Ibrahim used logical arguments in monotheistic argumentations. According to the carried out studies, one can refer to the argumentations in which exceptional and categorical syllogism have been used to prove monotheism.

Lotfallah Nabavi has reviewed Rescher's two major researches on Ibn Sina's temporal modalities and reflected the result in the paper "Nicholas Rescher and the formulation of Ibn Sina's theory of temporal modalities". While presenting Rescher’s first and second formulations, he proved the efficiency of R2 in the analysis of the universal modal compound propositions into two simple propositions, but did not independently analyze modal rules, whether simple or compound. Therefore, in order to verify his claim, the author has used the descriptive-analytical method to separately examine all the rules of simple modal propositions in Katebi’s inferential system. The results showed that in addition to the aforementioned efficiency, the R2 formulation has the necessary compatibility with the rules of simple modal propositions of Katebi’s logic. It was also made clear that it is not possible to prove some of Katebi’s arguments in Katebi’s system of modalities without considering the default qualification (∃x)(∃t) RtAx. This has never meant the incompatibility of Rescher’s formulation with Katebi’s theory, and has resulted from the necessary presuppositions of ancient logic in universal causal propositions. Another conclusion is that although material implication has not been the basis of logical inferences in ancient logic, our ancestors have always regarded it as a presupposition.

One of the divisions of proposition, which has been discussed in some of the later philosophical and logical books, is the division of proposition into definitive and non-definitive. Each of these two types - especially the nondefinitive proposition- has some rulings that can be used to solve some of the problems in logic and philosophy. Before these terms were coined, those problems were not easily solved, but when these kinds of propositions developed, an easy solution to these problems emerged. Of course, this type of proposition itself has faced challenges. After examining the concept and the truth of such propositions, this paper has discussed some of those challenges. In this study, some other issues such as conditional, conditioned and factual propositions have inevitably been dealt with in order to clarify their difference from this proposition.