Acceptance based on authority requires attention to the accuracy of attribution, the speaker’s competence and the relevance of that competence to the topic.
Example 1: a qualified physician gives a general precaution within medical practice.
Example 2: the same physician offers a personal opinion on an unrelated technical subject.
The person is unchanged, but the evidential value of the claim is not. When analyzing rhetorical premises, distinguish the social effect of a trusted speaker from the actual strength of the evidence.