عنوان مقاله [English]
Shams al-Din Samarqandi, a seventh Iranian logician, has proposed a new theory on conditional syllogism against Avicenna. Avicenna believed that conditional syllogism had only 19 valid moods; but Samarqandi, denying this similarity, validated only 7 moods. Samarqandi considered in his analysis only the quality conditions of the syllogism and did not pay attention to quantity conditions and in providing counterexamples for the invalid moods, he ignored their quantificational differences. If we consider just quality, as Samarqandi did, we’ll find a surprising similarity between his valid moods and the contemporary relevance logic, so that all Samarqandi’s valid moods are valid in relevance logic and vice versa. But if we look at the quantity of the propositions involved, we’ll encounter some difficulties, which are rooted in his interpretation of conditional quantifiers.