After identifying the four sources, legal theory examines their modes of operation. Seven connected questions show why that analysis matters.
1. The status of non-canonical recitations.
2. A transmitter's practice apparently contrary to a report.
3. The imperative and the presumption of obligation.
4. The authority of consensus.
5. A later agreement following a prior disagreement.
6. The basis of reasoning by analogy.
7. Weighing a subtler but stronger analogy against a more obvious one.
These are not merely academic labels. Before establishing a ruling, a jurist must determine whether the cited material is authoritative, what its wording indicates, and how evidence should be weighed when more than one consideration is present. That is the central role of uṣūl al-fiqh.