Informal Fallacy: Argumentum ad Verecundiam (Appeal to authority)

I. Argumentum ad Verecundiam: (argument from authority) the fallacy of appealing to the testimony of an authority outside his special field. Anyone can give opinions or advice; the fallacy only occurs when the reason for assenting to the conclusion is based on following the recommendation or advice of an improper authority.
	A. Occasionally, this argument is called the "argument from prestige" and is based on the belief that prestigious people cannot be wrong. In these cases, the fallacy is probably best termed the "snob appeal" variety of the ad populum.
	B. Sometimes it is difficult to distinguish between the ad verecundiam and the ad populum when the authority cited is a group with high status.
		This example from a popular logic text can be identified as either an ad verecundiam or an ad populum: "Those who say that astrology is not reliable are mistaken. The wisest men of history have all been interested in astrology, and kings and queens of all ages have guided the affairs of nations by it."1
	C. The informal structure generally has the basic pattern:
		Authority on subject x, L says accept statement p. p is outside the scope of or not germane to the subject x. p is true.
	C. For example:
		Linus Pauling as the only person ever to win two unshared Nobel prizes, one for chemistry, the other for peace stated his taking of Vitamin C delayed the onset of cancer by twenty years. (Winning a Nobel Prize in chemistry and for peace does not imply expertise in the medical science of the diagnosis and treatment of malignant neoplasms.) Therefore, vitamin C is effective in the treatment of cancer.
	E. Many advertising campaigns are built on this fallacy. Popular sports figures, musicians, or actors endorse products of which they have no special expertise and, in this context, this fact is offered as a mistaken reason we should use those products. Even so, occasionally a movie star, for example, might also be an appropriate authority in another subject. For example, Ronald Regan can be relevantly quoted as a political authority or Paul Newman can be quoted as a race car driver. Their reasoning in those respective fields would not ordinarily be open to the charge of an ad verecundiam fallacy.
	F. Note also that an ad verecundiam inductive argument (i.e., an argument whose conclusion is claimed to follow not with certainty but with probability) is not necessarily a fallacy even if the relevant or appropriate authority in the field is mistaken.
		For example, in 1948, readers of Science News were invited to buy a fluffy dish towel made from 80 percent cotton and 20 percent asbestos from "Things of Science," an experiment of the month program provided by Science Service.1 Concluding that the towel would be safe and useful would not have been an ad verecundiam fallacy even though the authority in this case, the Science News program, was being relied upon. The authority was relevant but simply mistaken.
II. Examples of the ad verecundiam fallacy:
		A. The brilliant William Jenkins, the recent Nobel Prize winner in physics, states uncategorically that the flu virus will be controlled in essentially all of its forms in the next two decades. The opinion of such a noted scientist cannot be disregarded.
		B. The United States policy toward mainland China in the 1980's was surely mistaken because Shirley McLaine, the well-known actress, emphasized at the time she had grave misgivings about it.
III. Uses of the ad verecundiam.
	A. Proper experts and authorities render valuable opinions in their fields and, ceteris paribus, should have direct bearing on the argument at hand—especially if we have no better evidence to base a conclusion securer grounds.
	B. To qualify as an authority, the individual must be generally recognized by peers in the same field by peers who either hold a similar view or recognize the cogency of the point of view being expresses. (Examine, for yourself, why this condition of citing what many authorities in a field believe is not an instance of the ad populum fallacy.) thanks to source: http://philosophy.lander.edu/logic/authority.html