I've blathered before about how much I hate the slippery-slope argument, usually trotted out when the arguer can't give a convincing reason about why something is bad, so they just claim it will lead to something worse. Of course, there are still more bad arguments.
Such as one from Rick Warren's PR machine. He is on the hot seat for saying recently regarding California's anti-gay marriage initiative, that he "never once even gave an endorsement in the two years Prop 8 was going," when there's a video of him saying publicly, "I urge you to support Proposition 8 and to pass that on."
The PR flacks tried to recover with this statement: "When Dr. Warren told Larry King that he never campaigned for California’s Proposition 8, he was referring to not participating in the official two-year organized advocacy effort specific to the ballot initiative in that state." (The link has all the quotes/videos.)
The PR spin is what I call the Unstated Qualifier Argument - a statement or promise that is incorrect or reneged actually included an unstated qualification that limited its scope to a smaller premise, commitment, or contingency that isn't refuted. I've encountered the UQ Argument a fair bit in my day job fighting developer schemes, and it often makes as little sense from them as it does from Warren's spin machine.
And then there's one vexing thing about the UQ Argument, which is that I've used it myself. The difference between a poor argument and a frivolous argument is the poor argument isn't always wrong, it's just overused. Mainly though, the one or two times I can think of where I've used the UQ Argument is in admitting that I communicated poorly, rather than trying to claim I'm simply right. The UQ Argument fails both when it substitutes for an admission, and when it's really a coverup after the fact for something earlier that was unqualified.
Anyway, I hope that calling out the unstated qualifiers and slippery slopes as the weak arguments they are will help limit their overuse, if only a tiny amount. Warren, it's time for an apology.