They said: ‘Our response is that two premises are indispensable. When one is stated, the other need not be mentioned because the person addressed already knows it. The speaker therefore omits it, having no need to state it.’ We replied: ‘We do not find two universal premises by which the truth of a conclusion is established. For when someone says, “Every living being is a substance, and every human being is alive,” the conclusion is: “Every human being is a substance.” Yet, to the intellect, saying “Every living being is a substance” is on the same footing as saying “Every human being is a substance.” In practical inquiries, they cannot find a conclusion that depends upon two self-evident premises. If that is the case, one of them suffices. We say to them: Show us two primary premises requiring no prior demonstration, by which a disputed point is established, with both premises more readily acceptable to reason than the conclusion. If you cannot find this, your claim is invalid.’”
Al-Nawbakhtī said: “I have asked more than one of their leading figures to produce such an example, but none has produced one. What Aristotle described is therefore neither found nor known.”
He said: “As for the two remaining figures he subsequently mentioned, neither is used in the form in which he constructed it. If they become valid by converting their premises until they revert to the first figure, then what has been said about the first figure applies to them as well.” End of quotation.
Ibn Taymiyyah said:
His point is that the other figures yield conclusions only by being reduced to the first figure, as explained earlier. Thus, the other figures and the derivation of their conclusions involve needless effort and difficulty, since the first figure can accommodate all affirmative and negative propositions