Sarcasm Is Not an Argument:
In the comment thread about Judge Sarokin's post on the Padilla case, commenter "Carl Levin" (most definitely not this Carl Levin) tries to use sarcasm to express the view that the people who think Padilla has been treated poorly are ignoring how dangerous he is. I think Levin's comments illustrate a lesson: sarcasm may be fun for its author, but it tends to be a really poor means of persuading someone who does not already agree with you.

  The problem with sarcasm is that it pokes fun at the other side without actually making an argument. If you happen to agree with the speaker's view already, this can be pretty entertaining: you don't need an argument, so you enjoy the affirmation of how smart you are and how dumb the other guy is. But what if you don't already agree? Well, in that case sarcasm doesn't tell you very much except about the nastiness of the speaker. The sarcastic comment rather suspiciously avoids addressing the merits, and is more likely to turn off the undecided than persuade them.

  Let's take a look at Levin's argument, which I have cut and pasted from his comments (not in their entirety, but close). Recall that Judge Sarokin's post expressed concern with the way that Padilla has been treated. Levin responds:
Boy am I glad to see that someone is finally becoming the voice of reason and shouting it from the rooftops. This guy Padilla, you know, he was just misunderstood. His character was defamed because people have been saying that he wanted to detonate a radiological bomb in a big city, and really, nobody has anything solid on him. We should let him go, and give him a job at Los Alamos.

And what's really shameful about his trip to the dentist at taxpayer expense is that he had to wear shackles and goggles. When I go to the dentist at taxpayer expense, I wear loafers and occasionally carry a pair of bifocals, and even a guy who was planning to detonate a radiological device in a big city should be afforded the same kind of care. After all, he's in our custody and the least we can do is make him feel comfortable.

You know, really one of the nicest things in the world that people have ever discovered is how to take a few ounces of radiological waste and pack it on the outside of some conventional explosives and then plant it someplace in a big city, like right next to a fountain or a fire hydrant, or drop it from a small aircraft, detonate it, and force hundreds of thousands of people to evacuate while billions of dollars are spent to clean it up. Why, Padilla could have put one of those right outside the entrance to the NYSE or at the Mercantile Exchange in Chicago and it would have been an incredible gift to all of us. That's why Judge Sarokin is so correct about the abomination about him being "prejudged" as an "enemy combatant."

Yup, just like [critics of the Bush Administration] say. I agree completely. The charges are baseless and even the first charges couldn't be proved. Therefore we should let him go. I'll see you in my moon suit.
  I think it's safe to assume that Levin's view is that Judge Sarokin is not fully recognizing the the threat that Padilla poses; Levin makes that argument by taking on the voice of one who thinks Padilla is not only not a threat at all, but actually "an incredible gift." The hope, I gather, is that we will see how obviously silly it would be to think that, and we will then associate that silliness with the position that Judge Sarokin actually took.

  But imagine that you're undecided of what you think of the Padilla situation. On one hand, you figure Padilla is probably pretty dangerous; on the other hand, you might want some proof of that beyond the President's say-so. In that case, how persuasive is Levin's string of comments? Not very, I would think. The comments poke fun and make the other side look silly, but they don't actually address the debate. My guess is that for a typical undecided reader, sarcasm like that is probably more likely to push them to the other position rather than bring them aboard your own.