On: What constitutes a true ad hominem argument?

[JoelSutherland]

It's also important to remember that the reverse is true:

http://www.nizkor.org/features/fallacies/appeal-to-authority...

[marcus → JoelSutherland]

Yes that is what PG always says.

[tptacek → JoelSutherland]

And also important that in arguments that devolve to appeals to authority, arguments about the arguers are not always fallacious.