Ad Hominem and Tu Quoque

Two of the most common fallacies in opinion writing — and therefore in LNAT passages — involve attacking the person making an argument rather than addressing the argument itself. These are the ad hominem fallacy and its close relative, tu quoque ("you do it too"). Recognising these patterns is essential because LNAT questions frequently ask you to identify flaws in reasoning, and personal attacks disguised as logical arguments are a favourite device of persuasive writers.

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The Ad Hominem Fallacy

Ad hominem (Latin: "to the person") is committed when someone rejects or dismisses an argument by attacking the character, motives, or circumstances of the person making the argument, rather than engaging with the argument's premises or logic.

Structure

Component	Description
Person A claims X	The argument or position being put forward
Person B attacks A's character	A personal criticism unrelated to the logic of X
Person B concludes X is wrong	The rejection is based on the personal attack, not on any flaw in X

Why It Is Fallacious

The truth or falsity of an argument is entirely independent of who makes it. A convicted fraudster can make a perfectly valid argument about economic policy. A hypocrite can give sound advice. Attacking the person tells us nothing about whether their reasoning is correct.

Key Principle: An argument stands or falls on its premises and logic, not on the character of the person who presents it.

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Types of Ad Hominem

1. Abusive Ad Hominem

This is the most straightforward form: directly attacking a person's character.

"Dr Singh argues that nuclear energy is the safest form of power generation per kilowatt-hour. But Dr Singh is funded by the nuclear industry, so his argument cannot be trusted."

The funding source may be relevant to evaluating potential bias, but it does not logically invalidate the argument. The data and reasoning Dr Singh presents must be evaluated on their own merits.

2. Circumstantial Ad Hominem

This form attacks a person's circumstances or interests rather than their character.

"The CEO of a pharmaceutical company says the new drug is safe. Of course she would say that — she stands to profit from its sale."

Again, financial interest is worth noting when assessing credibility, but it does not refute the claim. The drug may genuinely be safe regardless of who profits.

3. Guilt by Association

This form dismisses someone's argument because of their association with a disreputable group or individual.

"Jones has advocated for stronger press regulation. But the only other people calling for press regulation are authoritarian regimes. Jones's proposal should be rejected."

The fact that authoritarian regimes also restrict the press does not mean that all press regulation is authoritarian. The argument must be assessed on its specific merits.

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The Tu Quoque Fallacy

Tu quoque (Latin: "you too" or "you also") is a specific type of ad hominem that attempts to discredit an argument by pointing out that the person making it does not act consistently with their own position.

Structure

Component	Description
Person A argues for X	A position or recommendation
Person B points out that A does not follow X	Evidence of hypocrisy
Person B concludes X is wrong	The position is rejected because of the inconsistency

Classic Example

"The Health Secretary has urged people to reduce their sugar intake. But she was photographed eating cake at a party last week. Clearly, reducing sugar intake is not important."

The Health Secretary's personal eating habits have absolutely no bearing on whether reducing sugar intake is medically beneficial. Her hypocrisy may be worth criticising, but it does not affect the truth of her argument.

Why It Is Fallacious

Tu quoque confuses the validity of an argument with the consistency of the arguer. A smoker who tells you smoking is harmful is being hypocritical — but they are also being correct. Hypocrisy does not refute logic.

LNAT Tip: LNAT passages frequently feature opinion writers pointing out their opponents' inconsistencies as a substitute for engaging with the substance of the opposing argument. When you see this pattern, flag it as a potential tu quoque fallacy.

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Distinguishing Legitimate Credibility Concerns from Ad Hominem

Not every reference to a person's character or circumstances is fallacious. Context matters.