James Beck (assisted by Mark Herrmann) goes up against liberal proceduralist Stephen Burbank in a multi-round debate (PDF) at Penn Law's PENNumbra, and survives to tell the tale. A brief excerpt from their first post (most citations omitted):
...In 1955, the Advisory Committee rejected an amendment to Rule 8(a)(2) that would have required plaintiffs to state "facts constituting a cause of action." It did so not to endorse fact-free pleading, but rather because the Committee already viewed existing Rule 8(a)(2) as requiring "the pleader to disclose adequate information as the basis of his claim for relief as distinguished from a bare averment that he wants relief and is entitled to it."
In 1957, the Supreme Court weighed in, offering in Conley v. Gibson, 355 U.S. 41 (1957), an extremely liberal interpretation of Rule 8. Conley contained dictum that a complaint should not be dismissed "unless it appears beyond doubt that the plaintiff can prove no set of facts in support of his claim which would entitle him to relief." This phrasing invited abuse, since hypothetical "set[s] of facts" not even pleaded could prevent dismissal. Taken literally, the Conley dictum could make it impossible for a defendant to win a motion to dismiss, thus rendering Federal Rule of Civil Procedure 12 a nullity.
Some courts declined to read Conley literally and continued to hold "that legal conclusions need not be accepted as true on 12(b)(6) motions" and "that pleaders are not entitled to unreasonable factual inferences." Edward A. Hartnett, Taming Twombly, 158 U. Pa. L. Rev. (forthcoming 2010) (manuscript at 16), available at http://ssrn.com/abstract=1452875. They continued to dismiss complaints that plainly lacked merit. ...
They cite the bone screw mass tort litigation as one in which parallel actions were brought before two federal judges, one of whom dismissed the action as based upon implausible pleadings, the other of whom waved it forward. The second case inflicted millions of dollars in costs on defendants who included blameless doctors and their families before eventually being dismissed on summary judgment.