This convergence between the Muwahhidun and the Zahiris, stemming from the convergence of their methodologies and their principle of "usul" (foundations), led them to become a single front in the ongoing traditional methodological debate between the Zahiris and the Maliki jurists, attacking the "furu'" (branches) methodology adopted by these jurists. They jointly received attacks as being, in their view, among the people of Zahir. The joining of the Muwahhidun to the Zahiris in this debate created parity between the two sides, and the political factor on the part of the Zahiris, who faced a powerful and deeply rooted adversary in the Maghreb, was a stimulating element for the dialogue. This dialogue was, in reality, between the methodology of "furu'" and tradition, and the methodology of "ijtihad" (independent reasoning) and "usul".

This dialogue sometimes took a violent turn, as Al-Mansur did at times by banning "furu'" and burning their books, and at other times it took the form of argumentation, either through debate or through responses by authoring books and treatises.

We can say that this dialectical movement between the two viewpoints bore good fruit for jurisprudence. It witnessed richness in their material and an improvement in their methodology, by moving closer to the texts. It was no longer the naive jurisprudence that compared the sayings of the imams of the school to each other and ultimately attributed them to the narration of Ibn al-Qasim from Imam Malik. Rather, it began to rely somewhat on evidence and to consider high-level differences.

However, these signs of jurisprudential growth in the direction of "ijtihad" and "usul" did not last long to develop towards maturity. Instead, they faded when that parity was broken again.