Introduction
An authority is someone who is called upon to give his expert testimony about some matter under his competence. The credibility of an expert, of course, is directly proportional to his expertise in that area. A sports athelete pushing a particular soft drink is in no better a position to offer an opinion on the product than anyone else. On the other hand, all experts hardly agree with one another on any number of topics, religion included.
Definition
The fallacy that purports to argue a proposition using testimonial evidence when the conditions of credibility are not fulfilled.
Illustrations
Argument #1: According to the Reformers, the sole infallible rule of faith is the bible alone.
Argument #2: The Westminister Confession says: "Those whom God effectually calleth, he also freely justifieth: not by infusing righteousness into them, but by pardoning their sins, and by accounting and accepting their persons as righteous..." Therefore, the Catholic view of justification is false.
Diagnosis
Believing a proposition based solely on authority is not at all fallacious. In fact, it's quite logical, reasonable, and historical. The key is determining who has authority and who does not. That is the real question.
Antidote
The best way of addressing this issue in matters of religion is simply to ask: "what good is authority if everyone has it?"
John Pacheco
The Catholic Legate
April 5, 2002