مجله معارف منطقی
پیاپی 2 (بهار و تابستان 1394)

The Peripatetic formula of definition is based on the following principles: a) the possibility of knowing something by means of its essentials, b) the acceptance of Aristotelian ten categories and c) the acceptance of Aristotle's ideas of matter and form. The Peripatetic approach to definition has been criticized by such philosophers as al-FÁrÁbi and Suhrawardi. Suhrawardi claims that it is impossible for us to know things by means by its essentials and he invokes philosopher's words to prove his claim. He says that the criterion for a thing to be self-evident is intuition; external or internal. He is also critical of the theories of ‘ten categories’ and ‘matter and form’. Having rejected Aristotelian view of definition, Suhrawardi presents his own theory of 'nominal definition', regarding it as very useful in sciences. Contrary to real definition that is based on the essentials of things, nominal definition is based on the essentials of the concept in question. Other issues touched by this article are the assessment of Peripatetics and Suhrawardi's theories of definition and their limitations and flaws.

Dialetheism is the view that some contradictions are true. Being usually associated with the name of Graham Priest, this theory rejects the principle of non contradiction which, according to most philosophers following Aristotle, is the most fundamental principle in human thought. According to Priest, there is no good reason to accept the principle of non-contradiction and thus one can, in some cases, agree with the idea of the existence of contradiction. To prove his claim, he turns to some evidence that can be divided into three groups: historical, empirical and intellectual. The present article deals with empirical and intellectual evidence and relates and assesses the criticisms leveled against dialetheism.

Epistemic ascent is a discussion that can be posed both in judgments or propositions as well as in notions and conceptions. In this article, the writer deals with it only in the sphere of judgments or propositions. Being among the most important contemporary epistemological discussions, it is focused on by epistemologists. After defining 'epistemic ascent', the article seeks to find [new] methods and ways to grasping theoretical acquired knowledge and to shed lights on the ways and methods that are already available. On the other hand, a discussion is raised as to whether or not the methods and ways that were available in formal logic in ancient times could serve our purposes.

A prominent 7th century (AH) philosopher and logician, Najm al-DÐn KÁtibÐ QazwÐnÐ played an important role in the development of Avicennian logical school in the world of Islam. A knowledge of his logical ideas and thoughts helps us a great deal to learn about the views and methodologies of logicians who came after him. In addition to elaborating some of Avicenna's logical innovations, he developed his own peculiar logical theories. Following Avicenna's methodology of writing logic, he made his own contributions. The writer seeks to deal with some of KÁtibÐ QazwÐnÐ’s logical ideas which can be recounted in the form of the following statements: judgment is composite; not every conception is self-evident, and it is in no need of being acquired; mutual relationship between ‘signification of complete accord’ and ‘signification by association’ is doubtful; eight unities being necessary as conditions in contradiction are reduced to two unities; and physical proposition exists and it is valid on its own as a special proposition.

The division of knowledge into evident and acquired and the need for the acquired to end up in evident are among the current discussions in logic. The idea of knowledge as being evident and acquired is sometimes predicated of the ‘matter’ of knowledge or its ‘form’. The former is defined as a sort of knowledge whose acquisition needs no thought whereas the latter as a kind of knowledge whose acquisition is in need of thought and contemplation. Though there is some difference of opinion among logicians in regard with acquired conception and the instances of evident propositions, there is no disagreement among them on the definitions of evident and acquired knowledge. Though they have touched on the idea of being evident and acquired in treating the ‘form’ of thought, they have presented no clear cut standards in this area. They have given no explanation for the criterion for distinguishing evident from acquired in regard to the ‘form’ of perceptive knowledge, i.e. definition and description, though they have interpreted the idea that an argument (reasoning) is evident or acquired in ‘form’ as to know whether or not the conclusion is clear. The writer here studies the meaning of evident and acquired in the ‘forms of thought’ and particularly in those of reasoning and comes to the conclusion that ‘being acquired’ does not give any sense in the form of thought and reasoning. According to him, all forms of thought and reasoning are self-evident.

Demonstrations are divided into á priori and á posteriori, with the difference that in the former the middle term is a cause both physically as well as mentally whereas in the latter it is only a physical cause. Given in a priori demonstration the middle term is conditioned to be a cause of predication of major term to minor term (not a cause of the existence of the major term), a priori demonstration is divided into four categories all of which produce absolute and permanent certainty. A posteriori demonstrations are alsodivided into absolute and relative a posteriori demonstrations. The fact that they do not produce absolute permanent certainty does not lead us to say they are not demonstrations. The discussion presented here reveals that the division presented by al-FÁrÁbi and the definition MullÁ ÑadrÁ has provided for a priori demonstration is no longer acceptable. It also deals with matters concerning the meaning of a priori and a posteriori demonstrations, which are seldom touched. These issues include 1) the objections raised concerning some demonstrations and their relations with each other and the answers given to them, 2) the relation between the ‘middle term’ and ‘minor term’ in a priori demonstration, 3) the division of demonstrations into a a priori, a posteriori, absolute and relative demonstrations being intellectually quantified, and 4) MullÁ ÑadrÁ’s view concerning the reality of the ‘middle term’ in demonstration.

The nature of logic has long been a subject of investigation by thinkers. From the time of Aristotle who, for the first time, formulated syllogism to the present time when we see different logics founded on the basis of mathematical logic, most logicians have been dreaming for a universal logic. Influenced by later Wittgenstein, Stephen Toulmin rejects this approach and presents a model of argumentation in logic that pays attention to public views and common issues. Criticizing classical logic, he holds the view that such systems of logic do not have any place in people's ordinary life. The writer here deals with the Wittgensteinian criticisms leveled against classical logic by Toulmin bringing to light his model of argumentation in logic as well.