Ad Hominem Fallacy: Types and Examples

The ad hominem fallacy happens when someone answers an argument by attacking the person who made it, as if that attack proved the argument wrong. The Internet Encyclopedia of Philosophy (IEP) defines it as an irrelevant attack on the person arguing, offered as though it undermines their argument (IEP). The UNC Writing Center puts it more simply: the arguer goes after the opponent instead of the opponent’s argument (UNC Writing Center). Not every criticism of a person counts, though. Sometimes someone’s honesty, expertise, or interests really do bear on the question.

Why it’s a fallacy

An argument is only as good as its reasons and evidence. Calling someone a bad person or a hypocrite tells you nothing about whether their premises are true (UNC Writing Center). Purdue OWL describes it as attacking a person’s character rather than their opinions or arguments (Purdue OWL).

The IEP gives this example: someone waves off a teenager’s claims about 17th-century astronomy because she’s only fifteen. Her age might make her less credible as a scientific authority, the IEP says, but it doesn’t touch her reasoning. That has to be judged on the evidence (IEP).

An insult alone isn’t the fallacy either. Lander University’s logic guide says a personal attack is a claim, not a fallacy, and that name-calling becomes fallacious when it’s used to dismiss an argument (Lander University).

The main types of ad hominem

The table below lists the four types you’ll see most often. The examples are made up.

Type	What it does	Example
Abusive	Attacks a trait of the person, such as their character, intelligence, or morals	“Don’t listen to Sam’s budget plan. He’s lazy.”
Circumstantial	Points to the person’s situation or interests and suggests that’s the real reason for their view	“Of course the bike shop owner wants more bike lanes.”
Tu quoque (“you too”)	Rejects a claim or advice because the person doesn’t follow it, or answers a criticism by pointing to the critic’s own faults	“My doctor says I should exercise, but she doesn’t, so I can ignore that.”
Poisoning the well	Discredits someone before they’ve even made their case	“Before Jordan presents, remember he’ll say anything to get his way.”

Sources: IEP, Stanford Encyclopedia of Philosophy, Lander University.

Abusive

The abusive type says a view shouldn’t be accepted because the person holding it has some unfavorable quality (SEP). Lander lists the usual targets: character, morality, competence, or personality (Lander University).

Circumstantial

The circumstantial type claims a position comes from the speaker’s self-interest and not from good evidence (SEP). The IEP gives having a vested interest as an example of the circumstances these attacks point to (IEP).

Tu quoque

Sources describe this one in two slightly different ways. The Stanford Encyclopedia of Philosophy (SEP) and the IEP both describe rejecting a view or a piece of advice because the person giving it doesn’t practice what they preach (SEP; IEP). Lander describes a person accused of something who replies that the accuser has the same fault (Lander University). In both versions, someone’s inconsistency is treated as if it settled the question. The IEP says discovering that a speaker is a hypocrite is a reason to be suspicious of their reasoning, but hypocrisy alone isn’t enough to throw that reasoning out (IEP).

Poisoning the well

The IEP calls poisoning the well a preemptive attack meant to discredit someone’s testimony before they give it (IEP). Lander describes it as attributing prejudice or objectionable associations to an opponent so their future responses are discredited in advance (Lander University).

How sources group them

The categories aren’t fixed. The IEP treats both tu quoque and poisoning the well as kinds of circumstantial ad hominem (IEP). Lander lists tu quoque as a type of its own and says poisoning the well is “usually” an instance of the circumstantial type (Lander University). Both also cover close relatives such as guilt by association, which judges a claim by the people its arguer associates with (IEP; Lander University). Spotting the move matters more than getting the label right. For more fallacies of this kind, see our list of logical fallacies.

When questioning a person isn’t a fallacy

Lander says the argument against the person “is not always fallacious,” because someone’s character or circumstances sometimes bear logically on the issue (Lander University). The SEP says recent scholarship finds these arguments are sometimes used fairly and sometimes fallaciously (SEP). The IEP calls deciding whether an attack is relevant the main difficulty (IEP).

• Sometimes the trait is the very thing being decided. The IEP says a person’s sexual conduct is irrelevant to their reasoning about astronomy but relevant to whether they should lead a church, a mosque, or a city council (IEP).
• Sometimes you’re relying on the person’s word. Much of what we know properly comes from authorities. The IEP says leaning on one goes wrong when the person isn’t an authority on the subject, can’t be trusted to tell the truth, is contradicted by other authorities, or is misquoted (IEP). Lander points to witness testimony and notes that U.S. rules of evidence allow a witness’s credibility to be challenged on grounds such as bias, earlier inconsistent statements, and a character for untruthfulness (Lander University).
• The person may stand to gain. The IEP’s example is a proposal drafted by someone likely to profit from it. Asking for independent checks before accepting it isn’t a fallacy (IEP). The SEP adds a caution: just because something serves a person’s interest doesn’t mean it should be rejected (SEP).
• You may be holding someone to their own commitments. Pointing out that an opponent’s own admissions lead to a conclusion they reject isn’t always fallacious, according to Lander (Lander University). This is close to the term’s original meaning (see the FAQ below).

A quick test: is the person offering reasons you can check for yourself, or asking you to take their word for it? Doubts about their character or motives carry more weight in the second case. Our guide on how to evaluate sources has more on judging who to trust.

How to respond to an ad hominem

1. Steer back to the argument. The UNC Writing Center’s advice for writers is to stay focused on the other side’s reasoning and not their character (UNC Writing Center). Try asking: “Suppose that’s true about me. What’s wrong with the reasoning?”
2. Concede what’s relevant. If someone raises a real conflict of interest, admit it and offer evidence that doesn’t depend on you. That’s the kind of independent check the IEP calls reasonable (IEP).
3. Don’t hit back in kind. “You do it too” is its own fallacy. So is excusing one wrong because of an earlier one, which the IEP calls “Two Wrongs Do Not Make a Right” and counts as a type of ad hominem (IEP; Lander University).
4. Check your own replies. When an argument makes you angry, it’s easy to go after the person who made it. Before you answer, ask whether you’re responding to their point or to them.

A related move is misrepresenting someone’s argument so it’s easier to knock down. Our guide to the straw man fallacy covers that one.