

Definition:
While sometimes it may be appropriate to cite an authority to support a point, often it is not. In particular, an appeal to authority is inappropriate if:
(i) the person is not qualified to have an expert opinion on the subject,A variation of the fallacious appeal to authority is hearsay. An argument from hearsay is an argument which depends on second or third hand sources.(ii) experts in the field disagree on this issue.
(iii) the authority was making a joke, drunk, under duress, or otherwise not being serious
(iv) There is no supporting evidence or argument to justify the position. If O.J. Simpson (an expert on football) insisted that footballs were made of cabbage leaves that wouldn't constitute an argument to that effect.
Examples:
(i) Noted psychologist Elaine Johnson recommends that you buy the EZ-Rest Hot Tub. (She is not an expert on hot tubs.)(ii) Economist Alan Greenspan argues that going on the gold standard will lead to economic prosperity. (Although Greenspan is an expert, not all economists agree on this point, nor does his saying so make it true.)
(iii) We are headed for nuclear war. Last week Ronald Reagan remarked that we begin bombing Russia in five minutes. (Of course, he said it as a joke during a microphone test.)
(iv) My friend heard on the news the other day that The United States will declare war on Canada. (This is a case of hearsay; in fact, the reporter said that The United States would not declare war.)
(v) The Los Angeles Times reported that sales were up 8.1 percent this year. (This is hearsay; we are not in a position to check the Times' sources.)
Proof:
Point out that either (i) the person cited is not an authority in the field, or that (ii) being an expert in the field doesn't automatically make one right and insist that the argument advanced be addressed without the appeal to authority.
References:
Cedarblom and Paulsen: 155, Copi and Cohen: 95, Davis: 69
