Thinking Better, Part 5: The Ad Hominem

The ad hominem literally means, "Against the Man".  The ad hominem takes the following form:

  • Person A makes claim X
  • Person B makes an attack on person A
    • Person B attackes person A's character, circumstances, or actions
  • Therefore, claim X is false

The ad hominem is quite prevalent anywhere and everywhere you find debate, from politics to the world of health and nutrition.

Examples of the Ad Hominem

"Candidate Jane Jones's proposal is ridiculous.  She as caught cheating on her taxes in 2003."

Whether Jane was caught cheating on her taxes in 2003 is irrelevant to the validity of her proposal.

"Francis Bacon's philosophy should be dismissed since Bacon was removed from his chancellorship for dishonesty"

The fact that Bacon was removed from his chancellorship for dishonesty is irrelevant to the validity of his philosophy.

"Therefore we should close down the church?  Hitler and Stalin would have agreed with you."

In this example, the person creates an ad hominem through guilt by association (and I mean distant association).  The fact that Hitler or Stalin would have wanted the church closed down has no relevance to the validity of the reasons why someone may want to close down the church.

"She asserts that we need more military spending, but that is false; she only says that because she is a Republican."

A person's political affiliation has no relevance to whether or not military spending should be increased.

"Of course the Senator from Maine opposes a reduction in naval spending.  After all, Bath Ironworks, which produces warships, is in Maine."

This is another example where the person making the statement is creating an ad hominem through guilt by association.  The person is trying to imply that the reason the Senator opposes a reduction in naval spending is because it would harm Bath Ironworks's business.  However, the presence of Bath Ironworks in the state may have no relevance to why the Senator actually opposes a reduction in naval spending.

"Bill claims that tax breaks for corporations increase development.  Of course, Bill is the CEO of a corporation."

 Bill's position as a CEO has no relevance to whether his claim about tax breaks is true.

Examples of the Ad Hominem in Health and Nutrition

"This study saying Nutrasweet is safe is bogus.  It was funded by Nutrasweet."

I have often seen people automatically dismiss scientific research based on the funding source.  While there is evidence that studies funded by industry are more likely to show positive effects than studies not funded by industry, funding alone is not a valid reason to dismiss a study off-hand, and can be considered a form of ad hominem because you are questioning the character and honesty of the researchers involved in the study.  What many people do not realize is that studies funded by industry are often superior in methodological quality than studies not funded by industry.  The studies often have larger subject numbers, better controls, and better study designs.  The methodological rigor of a study is far more important than the funding source, and I will accept a well designed study funded by industry over a poorly designed study not funded by industry any day (assuming a situation where I only have those two choices).

Remember, researchers that are not funded by industry can have their own biases, whether it's because they're trying to secure grant funding, or due to personal ego, or because they have invested a large amount of time in a particular hypothesis to which they have become emotionally attached.  We cannot know what is going on in the minds of researchers, so we need to go on what we do know...the study itself.

People also need to remember that just because a company funds a study, does not mean the company had any role in the methods, results, or publication of the study.  My study on glutamine was funded by the supplement company EAS.  However, EAS had no role in the study design, methodology, data collection, analysis, write-up, or publication of the results.  We had mixed results (a benefit on nasal IgA but not salivary IgA), and we published exactly what we found.

A Recent Example From My Website

Over on my Health Sleuth blog, an individual named Tim commented on my blog post on Cobroxin.  Unable to provide evidence refuting my statements on Cobroxin or glucosamine, he presented a series of ad hominems.  He stated:

"You are obviously a Rush Limbaugh Republican"

This statement was not true at all, and even if it was, it would have no relevance to the validity of my statements regarding Cobroxin or glucosamine.

"Someone that did not make it in mainstream University Chemistry Courses."

This was also a statement that was not true (I had a 4.0 in my chemistry courses), and even if it was, it would have no relevance to the validity of my statements regarding Cobroxin or glucosamine.

A “self-proclaimed” Intellectual

This was an attempt at sarcasm (another form of ad hominem), despite the fact that I have never made any proclamations about being an intellectual, and even if I had, it would have no relevance to the validity of my statements regarding Cobroxin or glucosamine.

What you are actually interested in the some lost stock deal with the producers of Cobroxin that went bad for you.

Here Tim creates an ad hominem by inventing a motive.  Because I am a stock trader, he tries to paint a picture that I was criticizing Cobroxin because I had lost money on the stock of the company that sells it, or because I was trying to bring the stock price down.  Of course, I've never held a position in the company that sells Cobroxin, and even if I did, it would have no relevance to whether my statements regarding Cobroxin were true or false.  My statements regarding Cobroxin stand on the evidence and logic alone, not on my motives for making those statements.

Tim then goes on to claim that I have "no biochemical investigative experience."  This not true (as evidenced by my study on glutamine), but even if it was, it would have no relevance to whether my statements regarding Cobroxin or glucosamine were true.

The Ad Hominem...Once a Fallacy, Always A Fallacy

Personal attacks and character assassinations are nothing new.  The ad hominem is here to stay...just realize that it is not evidence for a claim or argument.  Make an effort to recognize it when people use it, and try to avoid its use yourself.

Related Articles:

Part 1:  The False Dichotomy

Part 2:  Confirmation Bias

Part 3:  Non Causa, Pro Causa

Part 4:  The Straw Man

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12 years ago

James, While technically you are correct about the misuse use of ad hominems against industry funded research, such as your own, you are incorrect that such research can be viewed in the same good light as academia sourced research. In court, there are times when the character of a man can call into question his honesty and his testimony in court. If a man is regular drug user and has been caught stealing repeatedly to feed his habit, it will be difficult to believe him when he tells the court that the officer that caught him doing drugs and robbing… Read more »

Fredrik Gyllensten
13 years ago

Great article James – I will do my best to not do personal attacks when discussing with people 🙂

13 years ago

Ahhhh… love this one!

jamie hale
13 years ago

I would say that Ad Hominen, is definitely one of the most popular fallacies encountered in the fitness industry. However, there are so many used by people in the fitness industry it is probably hard to determine the most common.

It should be pointed out, even when using a logical fallacy in an argument- and making the argument invalid- it is still possible to have a factual conclusion.

Jamie Hale says eating excessive calories will make you fat, therefore eating excessive calories will make you fat-
Appeal to Authority fallacy

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