Appeal to Authority, Popularity, and Tradition

Not all appeals to authority, popularity, or tradition are fallacious — but many are. The LNAT frequently tests your ability to distinguish between legitimate and illegitimate uses of these appeals. This lesson explains how each works, when each is valid, and how to spot the fallacious versions in LNAT passages.

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Appeal to Authority (Argumentum ad Verecundiam)

An appeal to authority cites a person, institution, or source as a reason to accept a claim. It is fallacious when the authority cited is not a genuine expert on the relevant subject, or when the appeal substitutes for evidence rather than supplementing it.

When Is It Legitimate?

Scenario	Legitimate?	Why
"According to the WHO, this vaccine is safe and effective"	Yes	The WHO is a relevant authority on public health
"Professor Chen, a leading geneticist, says the risk of gene editing is overstated"	Yes	Professor Chen is an expert in the relevant field
"My dentist says the new tax policy is unfair"	No	A dentist has no special expertise in taxation
"A celebrity chef endorses this financial product"	No	Culinary skill does not confer financial expertise
"Einstein believed in God, so God must exist"	No	Einstein's physics expertise does not extend to theology

When Is It Fallacious?

An appeal to authority becomes a fallacy when:

1. The authority is not an expert in the relevant field — a physicist's opinion on economics carries no special weight
2. The authority is cited in place of evidence — "Dr Smith says X" is not the same as presenting the evidence that led Dr Smith to conclude X
3. Expert opinion is treated as infallible — even genuine experts can be wrong; authority supports a claim but does not prove it
4. There is significant disagreement among experts — citing one authority whilst ignoring a contrary consensus is misleading

Key Principle: Legitimate appeals to authority cite relevant experts to supplement evidence. Fallacious appeals substitute authority for evidence.

Worked Example

"The government's new education policy has been endorsed by Sir David Thompson, a decorated military general. With his track record of leadership and strategic thinking, his endorsement should reassure parents that the policy will improve standards."

Question: The argument's use of Sir David Thompson's endorsement is:

A. A legitimate appeal to expert opinion on education policy. B. A fallacious appeal to authority, because military leadership experience does not constitute expertise in education policy. C. A valid argument because generals understand strategy and discipline. D. Irrelevant because endorsements are never meaningful.

Answer: B. Sir David's military achievements, however impressive, do not make him an authority on education. His endorsement is being used as a substitute for evidence about the policy's merits.

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Appeal to Popularity (Argumentum ad Populum)

An appeal to popularity argues that something is true, good, or correct because many people believe it, support it, or do it.

Structure

Component	Content
Premise	Many people believe/do/support X
Conclusion	Therefore X is true/good/correct
The flaw	Popular belief does not determine truth or correctness

Examples

"Seventy per cent of the public supports the reintroduction of capital punishment. This shows that capital punishment is the right approach."

Public support does not make a policy morally right or practically effective. At various points in history, majorities have supported slavery, opposed women's suffrage, and endorsed racial segregation.

"Millions of people use homeopathic remedies, which demonstrates that homeopathy works."

The number of users tells us about popularity, not efficacy. A treatment's effectiveness is determined by clinical evidence, not by sales figures.

When Is Popularity Relevant?

Popularity is legitimately relevant when the argument concerns what people want rather than what is true:

Argument	Popularity relevant?	Why
"Most citizens want longer library opening hours, so the council should consider extending them"	Yes	The argument is about public preference and demand, not about truth
"Most people believe the earth is round, so the earth is round"	Technically valid but badly argued	The earth is round because of evidence, not because of popular belief
"Most people prefer Brand X, so Brand X is the healthiest option"	No	Popularity has no bearing on nutritional quality

LNAT Tip: When an LNAT passage cites polls, surveys, or public opinion to support a factual or moral claim, check whether popularity is logically relevant to the type of conclusion being drawn.

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Appeal to Tradition (Argumentum ad Antiquitatem)

An appeal to tradition argues that something should continue because it has always been done that way, or that a practice is correct because it is longstanding.

Structure