On Mon, Feb 24, 2014 at 02:37:13PM -0500, Phillip Hallam-Baker wrote:
> Could we have an RFC to explain what is and what is not a valid ad-hominem
> argument?
There are no valid _ad hominem_ arguments. _Ad hominem_ is a short
name of a fallacious form or reasoning where one attacks the person
making the argument _instead of_ attacking the argument as such.
(More fully, of course, it's known as _argumentum ad hominem_.)
> Ad Hominem is a perfectly valid argument against claims of fact when made
> against the authority making the claim. "PT Barnum is a notorious liar' is
> a perfectly valid argument against a claim PT Barnum is making about having
> found a mermaid.
I think this is only sort of true. When Barnum is making his
argument, he's offering testimony ("I found a mermaid"). In this
case, pointing out that Barnum is a notorious liar is an attack on the
testimony. It's therefore not an _ad hominem_ because you're not
attacking the person speaking, but arguing about the premises of
Barnum's original argument from testimony. Even there, it'd be a
pretty weak argument, until you added, "Also, there are no previous
known cases of mermaids, and PT Barnum has refused to allow anyone
else to examine the alleged mermaid." Otherwise, you could as easily
use the premise "Barnum is a notorious liar" when Barnum says, "A
contradiction cannot be true."
The primary consideration is always relevance to the argument at hand.
That's why _ad hominem_ is usually classified as a fallacy of
relevance. It's also why I prefer to avoid the term _ad hominem_ in
favour of pointing out why something is irrelevant to the argument at
hand.
> The question at issue here is not merely the conclusion but the implied
> statement of the facts.
I disagree. The question is whether the argument against a given
position is relevant to the truth or falisty of that position (or its
supporting premises). In the case of an _ad hominem_, the irrelevance
lies with attending to the speaker instead of that which is spoken.
Best regards,
Andrew
--
Andrew Sullivan
ajs@xxxxxxxxxxxxxxxxxx