Reasoning by reputation
Reasoning by reputation is the act of assuming or claiming the rightness or wrongness of an argument based solely on the credibility of its source. This can take the form of a number of more specific fallacies:
While reputation can provide cues as to which arguments are more likely to be valid or invalid, it should not be considered evidence of such – much less conclusive proof.
It is reasonable to suggest that someone's argument should be examined with unusual skepticism due solely to that person's reputation, but this suggestion does not itself counter their argument. Using this suggestion as an attack should be taken as a sign that the attacker lacks a substantial argument.
It is also reasonable to suggest that a given person's argument may be accepted without further investigation due to their reputation and standing in a related field, but this neither establishes the truth (or reasonableness) of that person's argument nor precludes further examination of it.