deviding both the subjects and the predicates of the categorical propositions into actuality and verity, afzal al-din khunaji states the actuality-parts as adjectives, but verity-parts in three forms: as simple, as relational and as conditional. since the adjectives are formulated in modern logic by conjunction, we can formulate actuality-parts as conjunctions. verity-parts can be formulated at...

a controversy among the muslim philosophers about the domain of the extensions was that is the subject of the verity-propositions contained the impossible extensions or only all of the actual and possible ones. from ibn-sina to al-khunaji, there are explicit texts to the former view; but later logicians, starting with athir al-din al-abhari, were inclined to the latter. in this paper, we attamp...

khunaji and his companions get influence from fakhr al-din razi and classified quantified propositions into two kinds: factual and external. abhari added the third kind which was named mental. tusi and his companions refuted khunaji’s viewpoint. analysis and explanation of the historical development of classification of predicative proposition into factual, external and mental is the problem of...

for the first time in the history of logic, afzal al-din al-khunaji has found tautologies and contradictories among the verity and actuality propositions. these have been formalized and investigated in first-order logic and it has been shown that their perpetual truth requires the assumption of ‘the presupposed existence of non-existence.’ in this paper, i investigate the tautologies in second-...

for the first time in the history of logic, abd al razzaq al-jili (d. 570/1174), in the treatise al-lame fi al-shakl al-rabe, dealt with the modal syllogisms of the fourth figure. previous to him, dinha, the priest, and ibn salah al-hamadani had discussed the non-modal moods of the fourth figure. jili’s treatise deals only with simple modalities and ignores the complex ones. his pupil, fakhr al...