argumentum ad verecundiam
(also known as: argument from authority, appeal to false authority, argument from false authority, ipse dixit, testimonials [form of])
Definition: Using an authority as evidence in your argument when the authority is not really an authority on the facts relevant to the argument. As the audience, allowing an irrelevant authority to add credibility to the claim being made.
According to person 1, Y is true.
Therefore, Y is true.
My 5th grade teacher once told me that girls will go crazy for boys if they learn how to dance. Therefore, if you want to make the ladies go crazy for you, learn to dance.
Explanation: Even if the 5th grade teacher were an expert on relationships, her belief about what makes girls “go crazy” for boys is speculative, or perhaps circumstantial, at best.
The Pope told me that priests can turn bread and wine into Jesus’ body and blood. The Pope is not a liar. Therefore, priests really can do this.
Explanation: The Pope may believe what he says, and perhaps the Pope is not a liar, but the Pope is not an authority on the fact that the bread and wine are actually transformed into Jesus’ body and blood. After all, how much flesh and blood does this guy Jesus actually have to give?
Exception: Appealing to authority is valid when the authority is actually a legitimate (debatable) authority on the facts of the argument. In the above example, if Jesus testified that this was actually happening, I guess we’d have to believe him. The above example demonstrates the kind of subtle difference in being an authority on the idea of transubstantiation vs. the actual effectiveness of transubstantiation.
Tip: Question authority -- or become the authority that people look to for answers.
Variation: Testimonials are statements from, “authorities”, in the sense that they are said to know about what they are testifying to. In business, vendor-provided testimonials should not be taken too seriously as they can easily be exceptions to the norm or just made up -- as in, “John G. from Ohio says...”