Definition and Examples of an Ad Hominem Fallacy

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Dr. Richard Nordquist is professor emeritus of rhetoric and English at Georgia Southern University and the author of several university-level grammar and composition textbooks.

Ad hominem is a logical fallacy that involves a personal attack: an argument based on the perceived failings of an adversary rather than on the merits of the case. In short, it's when your rebuttal to an opponent's position is an irrelevant attack on the opponent personally rather than the subject at hand, to discredit the position by discrediting its supporter. It translates as "against the man."

Using an ad hominem fallacy pulls the public's attention off the real issue and serves only as a distraction. In some contexts it's unethical. It's also called argumentum ad hominem, abusive ad hominem, poisoning the well, ad personam, and mudslinging. The attacks serve as red herrings to try to discredit or blunt the opponent's argument or make the public ignore it—it's not just a personal attack but one stated as a counterattack to the position.

Ad Hominem Arguments That Aren't Fallacies

Just as there can be negative attacks (or insults) against someone that aren't ad hominem arguments, there can also be a valid ad hominem argument that's not a ​fallacy. This works to convince the opposition of a premise using information that the opposition already believes to be true, whether or not the person making the argument believes them as factual.

Also, if the point of criticism of the opponent is an ethical or moral violation for someone who'll be in a position to enforce moral standards (or claims to be ethical), the ad hominem might not be irrelevant to the point at hand.

If there is a conflict of interest that is being hidden—such as personal gain that has clearly influenced a person's position—the ad hominem could be relevant. Gary Goshgarian and colleagues give this example of a conflict of interest in their book "An Argument Rhetoric and Reader":

"The organizer of a petition to build a state-supported recycling center may seem reasonably suspect if it is revealed that he owns the land on which the proposed recycling center would be built. While the property owner may be motivated by sincere environmental concerns, the direct relationship between his position and his personal life makes this fair game for a challenge" (Gary Goshgarian, et al., Addison-Wesley, 2003).

Types of Ad Hominem Arguments

An abusive ad hominem fallacy is a direct attack on the person. For example, it occurs when the opponent's appearance is brought up in the discussion. You'll see this a lot of times when men are discussing positions of female opponents. The person's clothes and hair and personal attractiveness are brought up during the discussion when they have nothing to do with the subject matter. Looks and clothes never come into the discussion, however, when the men's points of views come up for debate.

The scary thing, as T.E. Damer writes, is that "most abusers apparently believe that such characteristics actually provide good reasons for ignoring or discrediting the arguments of those who have them" ("Attacking Faulty Reasoning." Wadsworth, 2001).

The circumstantial ad hominem fallacy happens when the opponent's circumstances come into play, irrelevantly.

A tu quoque fallacy is when the opponent points out how the arguer doesn't follow his or her own advice. It's also called an appeal to hypocrisy, for that reason. An opponent might say, "Well, that's the pot calling the kettle black."

Ad Hominem Examples

Political campaigns, especially the tiresome negative attack ads, are full of fallacious ad hominem examples (as well as just negative attacks, without any positions stated). Unfortunately, they work, otherwise, candidates wouldn't use them.

In a study, scientists had people evaluate scientific claims paired with attacks. They found that attacks on positions based on ad hominem fallacies were just as effective as attacks based on evidence. Allegations of conflict of interest were just as effective as allegations of fraud.

In political campaigns, ad hominem attacks are nothing new. Yvonne Raley, writing for Scientific American, noted that "during the presidential campaign of 1800, John Adams was called 'a fool, a gross hypocrite and an unprincipled oppressor.' His rival, Thomas Jefferson, on the other hand, was deemed 'an uncivilized atheist, anti-American, a tool for the godless French.'”

Examples of different types of ad hominem fallacies and arguments include:

• Abusive: During the 2016 presidential campaign, Donald Trump threw out one abusive ad hominem attack after another about Hillary Clinton, such as, "Now you tell me she looks presidential, folks. I look presidential," as if clothing were the important issue at hand.
• Circumstantial: "That's what you'd expect someone like him/her to say" or "That's, of course, the position a ___________ would have."
• Poisoning the well: Take, for example, a movie reviewer who dislikes a Tom Cruise movie because of the actor's religion and tries to impose negative bias in the audience members' minds before they see the film. His religious affiliation is completely unrelated to his acting ability or whether the movie is entertaining.
• Relevant ad hominem arguments: It was relevant to attack Jimmy Swaggart after he was found with a prostitute yet purported to be an advisor and leader on moral issues. But he's not alone as far as preaching morality and not behaving. Any congressman who purports "family values" and commits adultery, is caught with pornography, or hires prostitutes—and especially those who lie about it—is legitimately open for character attacks.
• Guilt by association: If a person expresses the same (or a similar) view as someone who's already viewed negatively, that person and the viewpoint will then be viewed negatively. Whether the viewpoint is valid doesn't matter; it's tarnished because of the person who's viewed negatively.
• Adfeminam: Using female stereotypes to attack a viewpoint is an ad feminam fallacy, for example, calling someone's viewpoint irrational because of pregnancy, menopause, or menstruation hormones.