  Ibn Kammuna communicated this “proof” to Nasir al-Din al-Tusi, who proceeded to uncover its  fallacies.[5] For example, the contraposed major premise, “whatever does not necessitate the denial of immediate reality is immediately real,” when written in its positive formulation, requires a rider: “Whatever is absent from immediate reality (ghayr waqi’, grammatically a positive sentence in Arabic) necessitates the negation of immediate reality, as long as it remains absent from immediate reality.” The rider, however, makes the premise hypothetical, and that, in turn, changes the rules as far as conversion is concerned, and does not allow the conclusion Ibn Kammuna wishes to draw.