I am simply amazed by the number of people here who think that ad hominem arguments are valid -- or maybe what I'm amazed at is the sheer quantity of time they spend making such arguments. Here I hope to explain, simply, what an ad hominem argument is, and how it functions.
Ad hominem argument, as follows:
Translated from Latin to English, "Ad Hominem" means "against the man" or "against the person."
An Ad Hominem is a general category of fallacies in which a claim or argument is rejected on the basis of some irrelevant fact about the author of or the person presenting the claim or argument. Typically, this fallacy involves two steps. First, an attack against the character of person making the claim, her circumstances, or her actions is made (or the character, circumstances, or actions of the person reporting the claim). Second, this attack is taken to be evidence against the claim or argument the person in question is making (or presenting). This type of "argument" has the following form:
1. Person A makes claim X.
2. Person B makes an attack on person A.
3. Therefore A's claim is false.
What's curious to me, here, is the number of people here who think this is a valid way to argue. The opposite is true: just because Cenk Uygur or Jane Hamsher or David Sirota or Rachel Maddow or Ed Schulz (or for that matter Grover Norquist or Joe Lieberman or Rand Paul) makes a particular argument ("claim X") does not mean that "claim X" can be dismissed outright because Cenk Uygur or Jane Hamsher or David Sirota or Rachel Maddow or Ed Schulz or Grover Norquist or Joe Lieberman or Rand Paul is a "tool" or "stupid" or "self-aggrandizing" or "mendacious" or whatever insult one might apply to anyone who makes an argument.
If you want to avoid the ad hominem fallacy, then, you will examine all arguments on their own merits, regardless of who or what is making them, and regardless of your reasons for hating them or disliking them or finding them otherwise "unreliable" or "untrustworthy" or "offering Republican talking points" or "not worthy of consideration." If you really want to "score points" in a debate, you will stay on the level of argument, and avoid bickering about personalities.
Examining arguments on their own merits, to be clear, means looking at the reasons to support each argument, and the implied presumptions hidden in each argument. Are people making claims that are true? (questions of fact) Can we call particular moral judgments into question? (questions of value) Would a particular action be efficacious or morally worthy or in some way constructive of the world we all wish to see? (questions of policy) -- these are the questions which are answered in meaningful, nutritious argumentation. Arguments do not count as "true" or "untrue" merely by virtue of whomever said them. "David Sirota (or whomever) sucks" is not a meaningful argument. It may express your true feelings, of course. But what about such an argument merits our attention?
Now, I recognize that politics is often a contest of personalities, and that we might like (or dislike) someone (and thus their arguments) based on their personalities. In fact, our political system supports this, with the selection process for members of the political class ("politicians") based upon "head-to-head" contests in which television attack advertising is typically used to denigrate the personalities of each of the likely winners. But the fact that "this is how it is" is part of a compelling case for CHANGING THE SYSTEM, rather than for conforming to its dictates. If we are electing our politicians based on ad hominem arguments, no wonder our system is screwed up.
The thing to remember is this: disagreeable people can make good arguments. Good people can also make bad arguments. It happens -- perhaps not most of the time, perhaps only rarely, but it happens.
Here I would like to distinguish the idea of an ad hominem argument from that of the personal attack. A personal attack is not an ad hominem argument. A personal attack occurs when you say that "so-and-so is bad" for whatever reason. Personal attacks are not ad hominem arguments. Of course, personal attacks contribute nothing to rational, civil discussion -- but they do not, by themselves, constitute ad hominem arguments. An ad hominem argument comes into being when one uses the implied presumption that bad people can only make bad arguments.
As I said above, I'm really surprised to see how many people here actually believe this.
I would also like to distinguish the idea of an ad hominem argument from that of an attack on someone's argument. An attack on someone's argument is not an ad hominem argument even when accompanied by a personal attack. It is certainly true that bad people often make bad arguments. George W. Bush, for instance -- his personality profile is written up in this book (and you can see that there were plenty of significant disqualifications for the Presidency there), and his arguments -- well, they were something to improve upon. Thus during the Bush era one could read plenty of arguments which both attacked Bush and the policies he promoted in his status as President. These attacks were not ad hominem arguments. It is ONLY, then, when you BASE YOUR CRITIQUE on the idea that the PERSON MAKING THE OPPOSING ARGUMENT is somehow "untrustworthy," that you are engaging in an ad hominem argument.
The way around the ad hominem argument, the ONLY way around it, is to EXAMINE THE ARGUMENT ITSELF.
When I taught "argumentation and debate" at The Ohio State University, a number of fundamentalist Christians wanted to make the argument in their papers that "gay marriage is immoral" based on the idea that the defenders of gay marriage were -- wait for it -- gays, and thus their arguments carried no weight. I was obliged to point out that, yes, you may write your argumentative paper on why "gay marriage is immoral." But when you address opposing arguments in your paper, you must regard these arguments on their own merits, without reference to the sexual (or other) identities of their authors.
Thus by the "rules of the game" in Communication 305 at The Ohio State University, Argumentation and Debate, ad hominem arguments did not "count."