Faulty use of authority: the writer relies on "authorities" who are not convincing sources. Although someone may be well known in a particular field, he or she may not be qualified to testify in a different area. A baseball player in an ad for laser surgery may stress his need for correct vision, but he may be no more knowledgeable about eye care than anyone else on the street. In other words, name recognition is not enough. For their testimony to count with readers, authorities must have expertise, credentials, or relevant experience in the area under discussion. (See also pages 285, 380-382, and "transfer of virtue" in the discussion of "bandwagon appeal" on page 288.)