Even when an authority passes these tests, be aware of lapses that may reveal the degree of knowledge possessed by an expert. Well known or highly honored scientists are commonly asked to comment on subjects outside their own field of expertise. These people should be subjected to exactly the same questions as an unknown authority. Does a Noble prize winner in physics, for example, have any credibility when making pronouncements about evolution? Maybe, but the evidence and hypotheses about evolution are very far removed from the usual literature of physics. Be suspicious. In your daily life, authorities are always present making one claim or another, usually to sell something. These claimants can be evaluated rationally too.