Project Logicality | Logical Fallacies: The Ad Hominem Argument

Let’s face it: almost nobody likes to be insulted, but that very thing may be used as a form of argument in more or less subtle ways, an irrelevant reasoning error: the ad hominem argument, or Argument to the Person.

This tactic is the counterpoint to the Argument from Authority, another genetic fallacy – arguments that focus on the source of a claim rather than good logic or evidence, and like it tries to call attention to real or imagined characteristics or the origin of the one making the claim or the claim itself, generally those that are negative or unfavorable.

A special case of this is called Poisoning the Well, the Circumstantial ad Hominem, often made even before the opponent makes their argument. This form links the target with someone or something that is widely regarded as unpleasant, distasteful, or evil, such as implying or stating a connection with people like Nazis, terrorists, or infamous serial killers.

The name of this subset probably derives from medieval Europe, when rumors abounded during outbreaks of plague that Jews were causing Christians to die from the epidemic by poisoning the local well water, since the real vectors of the plague were unknown at the time. This differs from the usual form in that it can be made against both a person and an idea or belief.

In that hideous little abomination of a movie, Expelled, there was much use of poisoning the well in the association of evolution, and science in general, with the Holocaust and with Nazis in particular.

The most common and least subtle form of this argument, used by those greatly lacking in imagination, is the use of verbal abuse to point out real or imaginary shortcomings as a cheap and easy way to dismiss an argument by dismissing the person making it. This is also known as shooting the messenger.

“Your argument is wrong because you’re a known religious fundamentalist.”


“I don’t have to listen to you because you’re one of those Godless heathens.”

…or my favorite,

“I don’t have to provide any references for what I said. You should just accept it as I said it, or you are an obstinate fool for questioning something so self-evidently true.”

Often used is a supposed conflict of interest, bias, or personal prejudice, the Bias ad Hominem, indicating that the target is untrustworthy as an impartial source, or as is often the case, of an American politician accusing his opponent of being a socialist or a fascist even when these claims are not only irrelevant but false.

Another is when critics of the modern anti-vaccination movement are implicated as paid shills in the pocket of the “Big Pharma” conspiracy, whose statements therefore must be taken with sinister intent in mind.

Still further is when mainstream scientists are accused of being afraid for their funding, careers, alleged political agendas, and reputations to ignore or hide “the truth” of the paranormal or global cooling.

Those last two, by the way, are also referred to as an argument from conspiracy, or an appeal to motive, another version of the bias ad hominem.

But the Ad Hominem argument is not always a fallacy, and in its proper use it may be a valid and effective form of argument when it is used to promote the goal of critical discussion rather than to obstruct it.

For example, a reasonable use is in pointing out a likely conflict of interest regarding the personal testimony of a claimant when the subject’s questionable background, credibility and circumstances are also true, relevant, and kept in their proper context, such as a disgruntled ex-gang member testifying in a criminal case when he has been given leniency or other favors for his testimony.

And this fallacy is more complex than one might think…

Less commonly known, and just as poisonous to an argument, is the positive ad hominem, which uses the same sort of reasoning, substituting claimed positive personal attributes, associations, or circumstances for relevant evidence in an argument, such traits as sincerity, kindness, or piety; any virtuous trait will do, although here it shades into an argument from authority/appeal to virtue.

Tf. Tk. Tts.

2 thoughts on “Project Logicality | Logical Fallacies: The Ad Hominem Argument

  1. _C_A_T_

    First thanks for the RSS/Linky-love in the upper Left-Hand-Corner there. I’ll Repay the favor when (and if I ever) get home. And great post, by the way.

    On the ad Hominem fallacy, which we are all guilty of from time to time, the “valid use” is actually pretty well-defined. In court, for instance, the rule of thumb is that “character is not an issue unless the defendant makes it an issue.”

    If someone is pretending to be someone that they are not it is your responsibility to call them out for it.

    Ergo, cdesign proponentsists Lawyer Phil Johnson and Moonie Theologian Jonathan Wells both claim that HIV is not the cause of AIDS. Their judgement has to be questioned, particularly when they essentially claiming that all of the genuine experts in the field are wrong.

    Some of the things Ben Stein has to say in his own field of economics need to be called into question due to his idiotic statements re Intelligent Design, again he is often at odds with most experts in the field. Yes, they could all be wrong but Stein now has a documented history of being sadly and profoundly misled so I don’t know about taking his advice in regards to the housing crunch ….


    1. You’re welcome about the RSS feed. Yep, I actually had a lot of fun with this post — and the preceding — I’m in the process of rewriting some of my older topical posts, like these two on logical fallacies, from earlier last year and resurfacing them on the home page periodically to keep them up to date. That, and adding my own LOLs to them where needed. Cats are awesome.


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