Appeal to authority

A famous footballer who recommends a pension fund is an authority on football. On pensions, he is one more person with an opinion.

Relying on experts is not the mistake

Most of what anyone knows comes from other people. You have probably never measured the distance to the Sun or tested a medicine yourself, and it is reasonable to trust astronomers and drug regulators on those questions. So an appeal to authority is not automatically a fallacy. The Stanford Encyclopedia of Philosophy describes the ad verecundiam fallacy as one that concerns appeals to authority or expertise, and explains that such an appeal goes wrong when authorities are treated as if they could not be mistaken, or when leaning on them replaces a person’s own responsibility to weigh the evidence.

Three ways the appeal goes wrong

First, the authority is outside their field. The Stanford Encyclopedia gives the example of non-experts who parade as experts where they have no special competence, as when celebrities endorse products or social movements. A made-up ad: “Olympic swimmer Kim says this phone has the best camera.” Kim may be the best swimmer in the country; that tells you nothing about image sensors.

Second, the authority replaces the evidence instead of pointing to it. In 1824 Jeremy Bentham wrote, as the Stanford Encyclopedia quotes him, that fallacies of authority in political debate occur when authority “is employed in the place of such relevant arguments as might have been brought forward.” “The minister says the new rail line will pay for itself, so it will” stops at the minister. A good appeal would continue: “and here are the passenger forecasts and costs the ministry published.”

Third, the authority is valued for status rather than expertise. The Stanford Encyclopedia notes that John Locke’s words for this kind of argument, such as eminency and dignity, suggest he had in mind authority based on social standing. The Port-Royal Logic of 1662 had already warned against believing that people “speak the truth because they are of noble birth or wealthy or in high office.” A title, a uniform or a large following is not a qualification.

Questions to ask

1. Is this person an expert in the field the claim belongs to?
2. Do other experts in that field broadly agree?
3. Is the person pointing to evidence you could check?
4. Does the person gain from your believing it?

A close relative is the appeal to popularity, ad populum, which the Stanford Encyclopedia describes as similar except that the source appealed to is popular opinion rather than a named authority: “Millions of people use this app, so it must be secure.” Popularity is evidence that something is liked, not that it is safe or true. On health, law and money in particular, the safe habit is to look for the official or professional source and to treat endorsements as advertising.