Al-Khunaji on the Conversion of the Verity Propositions

The first who discussed separately the conversion of the verity and actuality propositions was Fakhr Al-Din Al-Razi، but Afzal Al-Din Al-Khunaji criticized most of the logical rules introduced by Al-Razi on the conversions of those propositions and many criticisms of Al-Khunaji have been accepted by the later logicians. I have discussed the conversion of the actuality propositions in another paper and showed that in two cases، Al-Razi was wrong and Al-Khunaji was right; but on the other cases، their controversies is rooted in different interpretations of the terms involved. In this paper، I''ll show that similar fallacies and similar differences in interpretations have occurred; thus، Al-Razi insisted that in verity propositions، the affirmative modal propositions (but the two possible) were not self-converted and the negative perpetual ones had not conversions. In these cases، Modern Modal Logic supports Al-Khunaji''s judgments. In the other cases، I''ll show that Al-Razi have been taking the modal verity propositions with two modal operators and Al-Khunaji with one; and this is the secret behind the controversies on the conversion.