A New Analysis of Khajeh Nasir al-Din Tusi's View on Conjunctive Propositions

Providing a correct analysis and explanation of conjunctive propositions stated by Tusi, the representative of the line of predecessor in logic, is of particular importance. The following paper first states that Tusi’s coincidental conditional, in addition to being true to both sides, may have probable components of truth and falsehood. Then it shows that Tusi does not give credit to the conditional of presumed continuity, in terms of aspects. It also shows that the words of those who argue that he has doubted the simple conversion of necessity of affirmative are completely unjustified. A large part of this paper is devoted to the presumptions of Tusi in explaining the conditions of subjunctive components. The important obtained results lead us to the fact that: First, the quantifier in conjunctive is exclusive to the necessitation of true; Second, affirmative universal proposition precludes necessitation of true, the implicate of which is veridicality by necessity in the affirmative state; Third, the only application of necessitation of expression is in the argument by the absurdity of contradictory. Another important achievement of this paper is interpreting cogent negative in Tusi’s logic as implication of negation, not the negation of implication. This interpretation is important because in disjunctive propositions, negative disjunctive means negation of disjunction not disjunction of negation.