On the off chance that some folks who write blogs are (appearances notwithstanding) educable, may we take a break from our regular (or irregular) programming, to explain the meaning of "ad hominem"?
Many names have descriptive and referential content: this goes for "criminal," "moral cretin," "moron," and "liar." Many of these names (e.g., "moral cretin") can, of course, also be used metaphorically, though so used, they still have cognitive content, and the individuals to whom the names are attached either do or do not satisfy the descriptive content of the name metaphorically used.
The use of "names" is not an "ad hominem."
An "ad hominem" is a kind of argument, that is fallacious (though, in some contexts, may actually be fairly reliable: more on that in a moment). The argument has the following structure: X asserts Y; you attack X to undermine Y, e.g., you argue that because X is a certain kind of person, Y is false and/or ought not to be believed. (Note: the fallacy, strictly speaking, would be to conclude from facts about X that Y is false; concluding that Y ought not to be believed based on an attack on X can be reasonable, a point to which we'll return.)
"Reynolds beats his wife" is an insult; "Reynolds beats his wife, therefore you shouldn't believe anything he says" is an ad hominem. Reynolds may, indeed, beat his wife, but, in fact, say many true and justified things. (Of course, if Reynolds said, "I don't beat my wife," then you shouldn't believe that, but then the argument is also not an ad hominem--compare, "Reynolds dodged the draft, therefore don't believe him when he says he was drafted and served in the military.")
Once in a blue moon, I employ an actual ad hominem on this site. (There's one here in the Update, for example.) That I use unflattering descriptive names for individuals, however, while shocking to some who stumble upon this site (you folks ought to leave immediately!), is not an ad hominem. That I refer, e.g., to Bush & co. as "criminal war mongers" is an unflattering name, but it is also correctly applied to Bush & co.: their invasion of Iraq was a violation of international law (and there appear to have been war crimes committed as well), and they are, quite obviously, war mongers (e.g., they led the nation in to an unnecessary war on false pretenses). If one argued that because Bush is a criminal war monger, therefore one shouldn't believe anything he says, that would be an ad hominem, though as an epistemic rule of thumb, it might not be a bad one: it could be, for example, that someone who is a criminal war monger is far more likely to lie and distort about most topics, for reasons that are easy to imagine. In that sense, an ad hominem can be fairly reliable, namely, when the attack on the person has implications for that person's general credibility or reliability.
Which brings us to InstaIgnorance, an unflattering name (a "childish" name I've been told), but not, by itself, an ad hominem. It is offered as a description of a particularly well-known blog site: and the implication, clear enough I suppose (except to those policing good manners), is that the blog site increases one's ignorance, not one's knowledge base or understanding. To know whether the unflattering name is warranted, whether it is not childish but simply apt and descriptive, one would need to scrutinize the site and assess, on the merits, the claims made.
So, for example, InstaIngorance has recently addressed John Kerry's charge that a military draft is likely if Bush is reelected. If we peruse InstaIgnorance's comments and links, here is what we "learn":
1. That Kerry is "making bogus claims about restoring the draft" because he's doing badly in the polls.
2. That what shows it to be "bogus" is that "it's Democrats in Congress who are sponsoring bills to brink back the draft."
3. That this is really all about the "fact" that Kerry is doing badly in the polls.
In none of this is there any mention of the pertinent facts that support the conclusion that a military draft is highly likely unless there is a change in current policy. Indeed, we are told that it is Democrats who sponsored the bills reinstating the draft, but are given no context or explanation for this fact--for example, that all 14 sponsors of the House Bill voted against the Iraq War, and that the bills were thus, obviously, (foolish) strategic ploys to stop the rush to war by raising the specter of drafting the children of chicken hawks and rich folks. The ploy, of course, failed, but this doesn't change the crucial fact, namely, that the bills were a response to Bush's belligerent policies, just as the current crisis in military staffing is a consequence of those same policies. It is the Bush policies that make a military draft inevitable, not the fact that some anti-war Democrats made a bad strategic call.
In short: InstaIgnorance's posting leaves you with no pertinent knowledge base on the issue of a possible military draft.
This is but one example, but it could be multiplied, though I'm sure the exercise is unnecessary for my regular readers, and unproductive for my irregular ones. Hence the site is more aptly called "InstaIgnorance": the name is warranted (if you know nothing else, you will instantly be made more ignorant by perusing the site), and it is not an ad hominem.
To be sure, the warranted application of the name carries with it an epistemic rule of thumb: namely, be careful before you believe what InstaIgnorance says. But insofar as the application of the name is actually warranted, then there is still no ad hominem, just a reasonable epistemic moral drawn from the fact that the blog site in question satisfies the descriptive content of the name.