أن يجعل السائل ما جعله المعلل علة لما ادعاه من الحكم علة لضد ذلك الحكم
The respondent makes the very attribute used to prove a ruling into a cause of the opposite ruling.
One argument claims that because a fast is obligatory it requires specific designation in intention. The other employs the same notion of obligation while stressing that a time already legally designated for a fast may not need the same further designation as a makeup fast.
The real dispute concerns the relationship among obligation, a specified time, and designation in intention, not the isolated word “obligatory.”