Some theological arguments attempt to make an imam’s inspiration or alleged protection from error an independent source of certainty. What needs proof is how the claimed immunity or infallible inspiration of that particular individual has been established. Merely invoking the person’s standing does not complete the argument.
When an imam’s judgment is established through revelation or sound reasoning, the evidence has its own force. When the claim consists only of an inner prompting, its reliability for other people still requires justification.
The distinction is between respect for a religious authority and the authority of an argument: affirming someone’s merit does not automatically entail that every inward impression of theirs constitutes an independent, universally binding proof.