Logical Fallacies 101: Argumentum ad Hominem

Logical Fallacies 101 is a regular segment of the Skeptical Samurai blog that deals specifically with logical fallacies (an introduction to logical fallacies can be found here: https://theskepticalsamurai.wordpress.com/2009/05/13/logical-fallacies-101/ ).  It is my hope that Logical Fallacies 101 will help, you the reader, to both cultivate and expand your logic/reasoning skills and as a result become a better critical thinker. 

Today’s Logical Fallacy:

Argumentum ad Hominem (also known as an “ad hominem attack” or a “personal attack”)

An ad hominem attack is any type of argument that attempts to counter the claims of individual by attacking the individual making the claim rather than the argument being put forth.    

Put in a more linear fashion:

  1. Person A makes claim/argument X
  2. Person B makes personal attack on Person A, calling the character of Person A into question
  3. Person A’s claim/argument is therefore called into question as being a quality claim/argument

An example of an Argumentum ad Hominem is:

  • Person A: Despite what some people may think, I believe that homeopathy is actually an effective treatment modality!    
  • Person B: You are an idiot for thinking that.  Only an idiot would believe that homeopathy really works.    
  • Person A: I am not an idiot, I believe that homeopathic method allows the water to “retain the memory” of the diluted substance, thus explaining its effectiveness.
  • Person B: Only and idiot would think that water is capable of “retaining memory”!

It the above exchange we can see that Person A has made a claim and that Person B has responded.  Unfortunately, Person B is not focusing on the issue at hand, but instead is personally attacking Person A.  Thus Person B has committed at ad hominem attack

An example of an effective argument in the above exchange, minus the ad hominem attack, might look something like this:

  • Person A: Despite what some people may think, I believe that homeopathy is actually an effective treatment modality!    
  • Person B: Based on my understanding of science and the natural world homeopathy has no feasible mechanism of action.  Could you please explain to me how you think that homeopathy works?
  • Person A: I believe that homeopathic method allows the water to “retain the memory” of the substance that has been prepared/diluted.  I believe that this is an adequate explanation of the mechanism of action of homeopathy, and validates it as an effective treatment modality 
  • Person B: To the best of my understanding of the natural world, there is no way for water to “retain memory” of anything.  Your proposed mechanism of action has not been proven or supported by any well designed/controlled studies.  Additionally, your explanation is not consistent with the mountains of data in opposition to it.  Your proposed mechanism of action would require a complete redesign of our current understanding of science and the natural world.    

A review of the above interaction reveals an effective argument in which Person B addressed the issue/claim made by Person A, but did not attack Person A’s character (as in the 1st exchange) in order to make the argument.

Now you may be asking yourself…

Well why is an ad hominem attack such a bad thing, and why is it considered a logical fallacy?

An ad hominem attack is considered a logical fallacy because the character, circumstances, or actions of a person do not have a bearing on the truth or falsity of a claim/argument being made (although there are of course exceptions to that rule).  The ad hominem attack attempts to (whether consciously or sub consciously) shift the discussion away from the topic at hand and onto specific regarding the character of one or more individuals.  Put more simply, the ad hominem attack fails to actually address the topic/issue/discussion at hand. 

Now…

Go forth, thinking critically, and avoid fallacious arguments!

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8 Responses to “Logical Fallacies 101: Argumentum ad Hominem”

  1. artfulD Says:

    Ad hominem can be more persuasive than other methods of argumentation when dealing with issues where the emotional brain makes the decisions based on little more than confidence in its ability to do so. The logic that appeals to the rational brain clearly has no effect on most believers n homeopathy. They ARE in effect captives of their ignorance. They are in that sense idiots. They may also fear being reminded of that possibility by those they have reason to respect as clearly more successful in other areas of life.

    • theskepticalsamurai Says:

      You raise some interesting points and thanks for the comment.

      The ad hominem can be a presuasive type of arguement to utilize, but as i mentioned in posting…it is a logical fallacy. Consequently, despite how “effective” or “useful” it can be to an arguement, it is a fallacious way to argue.
      Regardless of how good (or right) your arguement may be, commiting a ad hominem attack damages your credability…and can derail an otherwise correct/effective arguement.

      • artfulD Says:

        It’s not fallacious unless it’s used fallaciously. You can manage to construct syllogistic arguments that are conclusively true using almost any form of recognized fallavy. The fallacies involve not their use but their misuse to achieve conclusions that will thus appear to be true. But if used to arrive at the truth without this deceptive use, there will be no fallacy. Another way to put it is that the fallacies lie in the total argumantation and not necessarily in any particular part. Do some research on this, as there’s little room here to make my best case here.

  2. theskepticalsamurai Says:

    Again interesting points! I will def take them into consideration.

    I would argee that you are correct in your statement that: “You can manage to construct syllogistic arguments that are conclusively true using almost any form of recognized falla(c)vy”, but that does not make your logic/reasoning correct. The use of a logical fallacy to support an otherwise “true” claim does not suddenly make your fallcious logic sound. The position that you are supporting is still “true”, but the process that you used to support/get to that conclusion is wrong. Put another way, the end result is correct but the process is flawed.

    Additionally, i do not agree with your statement that: “The fallacies involve not their use but their misuse to achieve conclusions that will thus appear to be true. But if used to arrive at the truth without this deceptive use, there will be no fallacy”. A fallacious arguement is a fallacious arguement regardless if you are supporting a “true” claim or one that it is “untrue”. I would agree that fallacies often refer to the misuse of an arguement in order to prove a “untrue” point, but a logical fallacy does not suddenly become a becon of reason because it is used to support a true claim.

    • artfulD Says:

      A “fallacy” is a mistake, and a “logical” fallacy is a mistake in reasoning. The recognized forms of fallacies represent those with the potential for such mistakes but if or when one is aware of that, those mistakes can be avoided by those with the skill to do so. These “fallacies” actually represent procedural rules, and you will find if you really examine the literature on tis that, as I said before, it’s not a fallacy to ignore a procedure if the proscribed structure can be adapted to obtain the same degree of accuracy as would use of the more formal procedures.
      The key is in the achievement of any deception involved. To be a fallacy, a type of reasoning must be potentially deceptive, it must be likely to fool at least some of the people some of the time. But if the structure avoids the deception, the argumentation can be correct. And therefor logical. Unless again you refer to formal rules rather than mistaken results.
      But in the end we may have to agree to disagree on what “logic” amounts to, because we have formal, inductive, abductive, fuzzy, boolean, bayesian – and fallacies are not even applicable to some of those forms

      • theskepticalsamurai Says:

        Again, extremely interesting and insightful comments! Thanks for taking the time to post them

        And you are correct we may have to agree to disagree at this point. I def can see where you are “coming from”…and that may be the issue here…where we are both “coming from”…
        We both seem to have a different understanding (or preception if you will) regarding logic and its process/application

        Would i be correct in assuming that you come from a philosophy and/or literature type background? (not there is anthing wrong with that…just curious is all.)

  3. artfulD Says:

    Evolutionary philosophy is probably as close as anything that describes my field of research. The study of how “intelligence” developed and of how different life forms use different elements of abstractive calculation in the process. Especially how all “brain” functions rely on inference. Few seem to really understand what inference is, let alone how it is a necessary part of all choice making apparatuses. The attempt by the Greeks and others to “codify” fallacious argumentative tactics was in my view meant to direct the use of inference toward more “predictive” results. But in doing so, they somewhat paradoxically gave more credibility to the true false form of classical logic than its predictability quotient warranted.
    (I don’t want to say much more about this as it involves a work in progress.)

  4. theskepticalsamurai Says:

    Again, thanks for the response. Very interesting to hear about your background and your thoughts about subject pertaining to the brain, intelligence, logic and logical fallacies…

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