- knowledge of the modes of proof.
As for the evidences, this means knowing the specific sharʿī ruling, not merely the general principle.
As for the causes, it means knowing whether the effective cause is actually present in the given case—or absent from it.
As for the modes of proof, it means knowing the procedural route by which a judgment is rendered when litigation arises.
Whoever falls short in any one of these three falls short in his judgment, and every judicial error can be traced back to one or more of them.
- Divergence among the scholars *
The scholars disagreed: Is every mujtahid correct, or is only one of them correct—the one whose view accords with the truth that is with Allah—while the other is mistaken?
Some held that both are correct, because Allah Most High grants a reward even to the one who errs; had he no share of correctness at all, no reward would have been allotted to him.
The majority of scholars, however, maintain that only one is correct, namely the one whose conclusion matches the truth intended by Allah. The reward given to the one who errs is for his zeal for the truth and the effort he expended in pursuing it.
The stronger position is that only one is correct. Allah knows best.