BENEFIT 136: What is the criterion for determining issues of ijtihad (مسائل الاجتهاد)?

Sheikh Yūsuf Al-Jazaa’iri hafidahullāh says (slightly paraphrased) "...Firstly, deeming this (teaching/working in free-mixed environments) to be an issue of ijtihād is disputable, because issues of ijtihad have been determined by scholars, such as Sheikhul Islam, Ash-Shinqiti, among others, to refer to: Issues lacking clear text, apparent evidence, and definitive consensus; these are the issues categorised as مسائل الاجتهاد. As such, one finds the evidences are in conflict in such issues, because there is no explicit texts or definitive consensus in the matter. As for the issue of free-mixing, there are explicit texts from the Quran, Sunnah, statements of the companions, and other scholars. Allah ﷻ says: {وَإِذَا سَأَلۡتُمُوهُنَّ مَتَـٰعࣰا فَسۡـَٔلُوهُنَّ مِن وَرَاۤءِ حِجَابࣲ} "And when you ask [his wives] for something, ask them from behind a partition." [Surah Al-Aḥzāb: 53] Similarly, Allah ﷻ says: {قُل لِّلۡمُؤۡمِنِینَ یَغُضُّوا۟ مِنۡ أَبۡصَـٰرِهِمۡ وَیَحۡفَظُوا۟ فُرُوجَهُمۡ} "Tell the believing men to lower their gaze and guard their chastity." [Surah An-Nūr: 30] Also: {وَقُل لِّلۡمُؤۡمِنَـٰتِ یَغۡضُضۡنَ مِنۡ أَبۡصَـٰرِهِنَّ وَیَحۡفَظۡنَ} "And tell the believing women to lower their gaze and guard their chastity." [Surah An-Nūr: 31] If lowering one's gaze is obligatory, then what about studying/working in mixed-gender environments where there is looking and more?! The Prophet Muhammad ﷺ said: "Beware of entering upon women," referring to foreign women. When asked about the in-laws, he replied, "The in-law is death." Therefore, entering upon foreign women is prohibited by this hadith, and because studying/working in free-mixed environments involves entering upon women, it is prohibited. This is not referring to incidental mixing, as in going to the market or boarding a bus, but mixing intentionally and willingly. Also, one of the female companion requested that the Prophet ﷺ dedicate for them a separate session because all sessions were mostly dedicated for the men. He agreed to setup separate sessions for them. This request indicates that they never used has segregated sessions. Otherwise, there would have been no need for her to make this request. And if this were a matter of necessity, as some claim, the Prophet Muhammad would have allowed the women to attend the men's gatherings. Furthermore, Umar ibn al-Khattab (may Allah be pleased with him) used to strike people with his stick if ever he encountered them free-mixing, as reported in Musannaf Ibn Abi Shaybah. Once he saw a pond where men and women were performing ablution together, so he struck them with his stick. Moreover, the scholarly verdicts of the various schools of thought are numerous. I have come across approximately eighty citations from scholars of various of the schools of thought, all of whom prohibit free-mixing." Source: https://t.me/almanhajussalafi/443