نشریه منطق پژوهی
سال پنجم شماره 1 (بهار و تابستان 1393)

For Different thinkers، throughout history، ‘The unknowable non-existent’ has had different meanings. However، despite these differences، the ordinary absolute non-existent in Muslim philosophy (ma‘dūm muṭlaq; non-existent in both the external world and in the mind)، can be expressed in this way: absolute non-existent is never existed in external world or in mind (rather it is impossible to be conceived in the mind)، neither detailedly nor un-detailedly، neither in perception nor in imagination and intellect. ‘The absolute non-existent’ leads us to a paradox which is usually called the paradox of informing from absolute non-existent; suppose that (P) is ‘The absolute nonexistent is unknowable’، since the very P is a kind of knowledge or information about the absolute nonexistent، so we are encountered to a paradox. In this paper I explore the roots of the ‘absolute nonexistent’ and the paradox in Greek philosophy; actually in Parmenides and Plato.

For Different thinkers، throughout history، ‘The unknowable non-existent’ has had different meanings. However، despite these differences، the ordinary absolute non-existent in Muslim philosophy (ma‘dūm muṭlaq; non-existent in both the external world and in the mind)، can be expressed in this way: absolute non-existent is never existed in external world or in mind (rather it is impossible to be conceived in the mind)، neither detailedly nor un-detailedly، neither in perception nor in imagination and intellect. ‘The absolute non-existent’ leads us to a paradox which is usually called the paradox of informing from absolute non-existent; suppose that (P) is ‘The absolute nonexistent is unknowable’، since the very P is a kind of knowledge or information about the absolute nonexistent، so we are encountered to a paradox. In this paper I explore the roots of the ‘absolute nonexistent’ and the paradox in Greek philosophy; actually in Parmenides and Plato.

Avicenna believes that existence is either objective or subjective. Indeed، in his view، the existent and object are never separated from each other and their discrimination is analytical and intellectual; existent and object are Mosaveqat. In other words، what is thing exists and what exists is an object. In contrast to the Islamic Theologians، the objecthood is wider than existence، because Sabetat about which we have knowledge do not exist; so there should be a kind of realization and permanency beyond the existence. In the current century، in the tradition of analytical philosophy، Nathan Salmon with Non-serious actualism approach and by using free logic believes that the object is what has property; either existent or nonexistent. The objecthood of object is based on having property، rather than the existence.

In a paper entitled ‘the paradox of informing from absolute known; analyzing the concept of information’ we attempted، through a new approach، to find a new solution to the paradox of informing from absolute unknown. In his paper ‘A critique of ‘the paradox of informing from absolute unknown; analyzing the concept of information’’ Asadi has tried to challenge our arguments. However in his paper we have found some incorrect and superficial analysises، weak criticisms، and misunderstanding of some of our ideas.

In Metaphysical Foundations of Logic، Heidegger analyzes Leibniz''s doctrine of judgment down to basic metaphysical problems to show that how any kind of logic founds its grounds in metaphysics. After questioning the relation between being and thought، he describes the structure of judgment in Leibniz''s theory of judgment and refers to its historical origin. He demonstrates that concepts like subject and predicate and their relation in proposition or judgment and also the definition of truth in Leibniz''s thought are grounded in metaphysical theories. Yet one of the most important Leibniz''s concerns was the independency of logic from metaphysics to build his metaphysics on the basis of such logic.

Diodorus is a famous Megarian philosopher. He defines modal notions (necessity، impossibility، and possibility) in terms of temporal concepts. These definitions are consistent with his deterministic position. Among his modal definitions what is more discussed is possibility. He defines possible as that which either is or will be. In other words there is no possible thing that never be actualized. This definition is not commonsensical، so he supported his position with an argument called the Master Argument. Nowadays some have tried to reconstruct Master Argument with modern logic. Here we want to peruse two of them، i. e. Prior، Rescher.