A comment by a new poster over at Huff (which for whatever reason appears nowhere on her page or on mine or on the post) suggested that I needed to be schooled in critical thinking skills because I had refused to listen to Gary Null's exchange with Wakefield (or look at Mike Adams's idea of exoneration of Wakefield--I have looked and it's not).
And the comment above, as the poster noted in a comment that only she and I may know about, is indeed an ad hominem taken alone. Oops. Yup. I did it. It was a throw-away comment written in response in to a person who makes some of the more extreme people at Age of Autism almost look stable.
I wrote yesterday about how we have a tendency to use schemas; they are handy shortcuts, necessary tools that are often unconsciously created. They may also be intentionally constructed, which is what I detailed yesterday; if you use quack sites which have repeatedly been demonstrated to be based on misinformation or falsehoods, I know where you've gotten your information. I've already evaluated the evidence, and so in that case, since the information isn't new to me, I don't have to give it current, due consideration. In other words, although the statement taken alone is an ad hominem, if I had taken the time to detail as I did in yesterday's post (it was pretty long, wasn't it?), and then concluded with the quote at the top, the quote would no longer have been an ad hominem.
But I've also written recently that it isn't the person making the claim; it's the claim itself and the evidence for the claim. I've argued that the evidence matters, not the person, and this is true. When one's been reading the quack sites for as long as I have (plenty of folks far more illustrious than I-- a warranted and non-fallacious appeal to authority, by the way--have been reading the sites for longer and fighting the woo for longer), the claims become intimately familiar. In the over 800 posts here, I've spent time deconstructing the claims made at these quack sites (like natural news or Mercola's), and in that case, although it takes on the short hand of ad hominem to say that relying on Mike Adams or Gary Null to prove Wakefield's sainthood reveals Marsha's reasoning skills, well, in truth it does. Plus, if one did a search for moffmars (her old handle) here, you'll see I've rebutted her often over-the-edge remarks.
However, and no surprise, based on my last post on schemas and filing folks accordingly, I would argue that when coupled with extensive familiarity with certain writers/commentators/celebrities and their claims, although, yes we should consider claims and not rely on the person making the claim in general, we would be fools once we've analyzed several claims by a person and found the person to be either wholesale misinformed (to be nice) or outright fraudulent (still being nice) to rely on that person for important information.
It doesn't mean that the person won't be right on some things but it does mean that they are suspect enough to avoid reading them to gain helpful information. Better instead to go to the experts themselves than people who have clear agendas to sell more products (ah, and all the anti-vaccine folks scream, yes like big pharma).
Hyman, for instance, isn't wrong on everything, but he's still not where I'm going to get my health information from, and Lanza, speaking about stem cell research, may be well worth listening to, but as long as he's peddling biocentrism as an explanation for why we never die, I'm going to use my handy, dandy schematizing and file him accordingly. In other words, when the preponderance of evidence favors categorizing someone as a wackadoodle (again, being nice), well, it's reasonable to not waste time reading the wackadoodle's "evidence." Instead, I'll go to the experts.
So, GMC's Fitness Panel carries more weight than Wakefield's protestations on radio shows of fringe nuts Gary Null and Alex Jones (link on Null to quackwatch article on him; Jones link to the interview with Wakefield, hosted on natural news--there's a schema there).
Still, left on its own, I must admit that my comment meets the criteria of an ad hominem. As such, I would refer the commenter to my post on schemas as further explanation.