Originally Posted by Scott A Martin
An ad hominem is never relevant to an argument. If a person is arguing with an appeal to their own authority, e.g. I assert that x happened and put forth my grand integrity as proof, then you may point out my long well known reputation for being a liar. However, that is only an attack on the source and not on the argument itself. It says maybe we shouldn't put so much faith in my claim. However, it does nothing whatsoever to disprove that x happened. See the Wikipedia entry for more info on this.
But I digress. What happened here isn't even an ad hominem. The OP didn't make an argument. He just posted an announcement about Beck and a bunch of people who dislike Beck saw this as an opportunity to unleash their vitriol toward him.
There's a difference between ad hominem and questioning someone's credentials.
I am questioning how some guy who doesn't even have an academic degree can attempt to educate us in a "university." I'm not saying people who don't have degrees don't have things to teach, but on matters of academia? No.