Personal criticisms and logical fallacies

[Alf P. Steinbach]

* Ben Finney:
> Steven D'Aprano <steve at REMOVE-THIS-cybersource.com.au> writes:
> 
>> An ad hominem attack is not when somebody makes a criticism of you
>> personally. It is when somebody says something along the lines of
>> "Don't pay any attention to Alf, he doesn't know what he's talking
>> about, he's a <whatever>".
> 
> In other words, a criticism of the person is only a fallacy if it is
> both irrelevant to the argument *and* used to dismiss the argument.

Or to weaken an argument, or to draw attention away from an argument, or to 
weaken future arguments...

However, although in this particular case the Ad Hominems constituted logical 
fallacies, not all Ad Hominems are logical fallacies.

For example, if a person is a chronic liar, has a known history of lying, then 
that can have a strong bearing on whether the person's claims  --  technical or 
about other persons  --  should be seriously considered[1].


Cheers & hth.,

- Alf



Notes:
[1] As explained at <url: 
http://www.nizkor.org/features/fallacies/personal-attack.html>