Posted by Jonathan Adler:
On Ad Hominem Arguments:
http://volokh.com/archives/archive_2007_02_04-2007_02_10.shtml#1170708620
In the discussion over whether there is something scandalous about
[1]AEI's effort to commission analyses of the IPCC report and proposed
climate report, more than one commenter sought to defend the use of ad
hominem arguments. For instance, "Justin" [2]commented:
The "ad hominen criticism is wrong" argument is thorougly
erroneous, as I have discussed before. When the reader, either
because the evidence is withheld or too complex for him to
understand, on a particular challenged argument, is expected to
agree by trusting or distrusting the source, an ad hominen
attack/ab hominen defense is all you have to go by.
In [3]a bit of snark, I paraphrased this claim as "Ad hominem
arguments are convenient for the lazy and uninformed." Even put this
way, the claim has some truth, but all it means is that ad hominem
evaluations have some utility as a time-saving, filtering device for
those who lack the time or ability to evaluate the substance of a
claim on its merits. It does not say anything at all about the truth
or falsity of the claim itself. In other words, it does not establish
that ad hominem arguments are valid arguments.
Put another way: While it may be reasonable in some contexts to say:
"I trust information and arguments from X more than from Y because Y
is [corrupt/bought/of the wrong ideology/etc.]", it is a logical
fallacy to say "Y's argument is wrong" for the same reasons. The
strength or weakness of Y's argument can be evaluated independently of
Y's personal failings.
So, if I want to know something about the health risks fo smoking, and
lack the time, inclination, or ability to research the question for
myself in any detail, I may decide to trust the word of a medical
professional over that of a tobacco lobbyist -- and I will make this
decision because one is a medical professional who is concerned about
encouraging good health and preventing sickness, while the other may
have a financial incentive to gloss over the harms caused by his
product. The truth or falsity of each person's claims, however, are
independent of my evaluation. In this context, ad hominem information
serves as a time-saving heuristic device, but that is all.
In the context of blog comment threads, I think it reasonable to
presume that those who rely upon ad hominem arguments typically do so
because they lack the time, inclination or ability to mount more
substantive critiques. This is particularly the case where the
argument is utilized for purposes beyond the dismissal of an appeal to
authority. [After all, if one person in a debate wants to take the
short-cut of appealing to an authority instead of spelling out an
argument, it is reasonable to point out why the authority in question
might not be so authoritative.] Blogs like this one aspire to be
forums for reasoned discussion of various questions. Whether or not we
succeed in our aims, that discussion requires engaging subjects on
their merits, not resort to logical fallacies like the standard ad
hominem.
References
1. http://volokh.com/posts/1170541963.shtml
2. http://volokh.com/posts/1170541963.shtml#184961
3. http://volokh.com/posts/1170541963.shtml#184969
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