Three best-selling liberal authors have come up with a clever tactic: Use humor to shield hate, cynicism, and unsupported accusations. Those who object just don't "get the joke." Al Franken calls Karl Rove "human filth," Ari Fleischer a "chimp," and John Ashcroft "something of a nutcase." Michael Moore calls President Bush a "nitwit" and (in the voice of God, no less) a "devil." Molly Ivins manages to insult millions at once when she approvingly quotes William Brann's crack that "the trouble with our Texas Baptists is that we do not hold them under water long enough." Mean-spirited, you say? No,...