ثم إنما يعرف كون المعنى علة بالكتاب، وبالسنة، وبالإجماع، وبالاستنباط
The effective-cause status of a meaning is known through the Quran, Sunnah, consensus, or disciplined inference.
Quran: textual indication links an attribute to a ruling.
Sunnah: Prophetic clarification supplies a relevant cause.
Consensus: qualified agreement establishes its legal significance.
Inference: a jurist identifies a suitable cause from the evidence.
These approaches have different evidentiary strengths; inferred causes require particularly careful testing.