How can the existence of disagreement on certain issues be reconciled with the نقل (transmission) of scholarly consensus (ijma') on a single opinion regarding them, and is this consensus sound?

The نقل الإجماع (transmission of scholarly consensus) comes with the establishment of a differing opinion in several forms:

1. When the consensus was valid prior to the dissenting opinion, such as the consensus on the prohibition of musical instruments before Ibn Hazm.

2. When the consensus is valid, and the dissenting opinion is not considered, such as the consensus that the blood money (diyah) for a woman is half that of a man, or the consensus on the sphericity of the Earth, or the consensus on the prohibition of musical instruments according to those who do not consider Ibn Hazm's dissenting opinion.

3. When the scholar who transmitted the consensus holds the view that the opposition of one or two individuals does not invalidate the consensus, as is the case with Ibn Jarir al-Tabari and Ibn al-Mundhir, contrary to the majority of scholars who believe that consensus is only established by the agreement of all mujtahids (qualified jurists).

4. When the claim of consensus is not valid due to a pre-existing disagreement, such as the claim of consensus that a triple divorce uttered in one phrase counts as three divorces, whereas the Qur'an, Sunnah, Qiyas (analogical reasoning), and ancient consensus indicate that it is one, and that the change in fatwa during the time of Umar was for the sake of public interest. Another example is the claim of consensus on the dislike of Qaza' (shaving parts of the head and leaving others).