The Philosophers' Playground and a commenter point us to an article in Scientific American Mind by two Philosophers (Robert Talisse and Yvonne Raley) on two related logical fallacies–the straw man and, get this, the weak man. Everyone is familiar with the straw man. It's what I (perhaps unhappily) tend to call a fallacy of criticism. In order to defeat an opponent one caricatures the opponent's view, defeats that caricature, and then claims victory over the opponent's real argument. As the authors correctly point out, it's fairly common. We have (on our very unscientific survey) identified 109 instances of it. If we push the fight and defeat analogy a little bit, we might say that the straw man is the equivalent of pummeling someone named "Mike Tyson" (but not the one who is a boxer) and claiming that you beat up the real Mike Tyson. That's about how relevant your victory will be (even to the Nevada Boxing Commission).
The weak man works in a related fashion. Only this time instead of caricaturing an opponent's view, one picks on the weakest of an opponent's arguments, easily defeats it, and claims victory over the opponent's real view. Here's what the authors of the article say:
In what Talisse dubs a weak man argument, a person sets up the opposition’s weakest (or one of its weakest) arguments or proponents for attack, as opposed to misstating a rival’s position as the straw man argument does.
So rather than fight a fully rested Mike Tyson, you drug him, get him to "agree" to a fight, then beat him up. There, you beat up Mike Tyson, but it's not a victory to be proud of.
It seems to me there are two ways to look at this (at least). In one sense, it's not a fallacy unless you claim that you've defeated a stronger argument than you have. Defeating a weak argument someone actually makes isn't a crime. Lots of real arguments offered by real people are bad.
In another sense, however, the fallacy seems to consist in exchanging the weak argument for the strong argument. And that seems to be to be just what the straw man does. The straw man, after all, consists in the switch at the end–you exchange the defeat of a weak argument for the defeat of the strong one. The only difference is that the opponent in the weak man case gives you the weak version of his argument.
Perhaps there is another difference I'm overlooking. Anyone? A more formal paper (co-authored by Talisse) on the subject can be read here.