David Foster Wallace once invented an organization called the “Militant Grammarians of Massachusetts” whose members boycott stores with signs reading “10 items or less.” It was a joke (from the novel Infinite Jest), but it’s not too far-fetched. Eats, Shoots & Leaves, a book that took as its primary subject the misuse of various punctuation marks, became an international best seller a few years ago, and on bookstore shelves today it has plenty of company: Between You and I: A Little Book of Bad English; The Grouchy Grammarian; The Dictionary of Disagreeable English; Lapsing Into a Comma, and so forth.

These books tend to be written by prescriptivists—people who would dictate how language should be used. Descriptivists—those who would describe how language is actually used—have rarely had such eloquent (or prolific) spokesmen. As a result, they’re often ridiculed. Wallace, who himself is a somewhat militant grammarian, has argued that descriptivism is hopeless as a scientific endeavor: Using what people actually say and write to determine appropriate English usage is, he says, like writing an ethics textbook based on what people actually do. But descriptive linguists have finally found persuasive champions in Mark Liberman and Geoffrey Pullum, who have collected a series of essays from their blog Language Log into a new book, Far From the Madding Gerund.

The two bring usefully different styles to their arguments. Pullum, a syntactician at UC-Santa Cruz, can be vicious (and very funny), whether criticizing inept usage or demolishing prescriptivist myths. Liberman, a phonetician at Penn, takes a more data-driven approach, analyzing modern vocabulary, pronunciation, and grammar with custom-written computer scripts and plain old Google. (I’ll confess here that since interviewing Liberman and Pullum last year, I’ve struck up an occasional e-mail exchange with them. They mention me among many others as a “correspondent” in Gerund’s preface.)

Pullum’s essay ” ‘Everything is correct’ versus ‘Nothing is relevant’ ” offers an articulate defense of descriptive-language science. The caricature of descriptivism is that “everything is correct”: If a native speaker says something, it is ipso facto OK. This is “utterly insane,” says Pullum. English has rules (which he lays out elsewhere, as co-author of the 1,860-page Cambridge Grammar of the English Language), and descriptivists do believe people can misuse those rules; when they do they miscommunicate or just sound silly.

But linguists imagine rules very differently than Wallace-style militant grammarians, deriving them from observation of some of the billions of words spoken each day and analysis of the trillions that have been written down. They might observe native speakers undetected, record them in casual conversation, ask them what sounds grammatical to them, or observe what educated people write. If a sentence strikes the vast majority of speakers of a language as well-formed, it is well-formed. This doesn’t rule out variation, say, by dialect or region. “The team is in trouble” is grammatical in standard American English. “The team are in trouble” is grammatical in Britain. And linguists would say, “The team in trouble” is grammatical in African-American English—it is perfectly comprehensible and, crucially, native speakers of the dialect will not bat an eye at it. But “The team am in trouble,” even if comprehensible, is grammatical nowhere. Such a sentence could only be the product of a mistake or a joke. Descriptivists draw their rules from native speakers, but that doesn’t mean anything goes.

So, where do prescriptivists get their rules? Either they repeat what they were taught, or they refer to “authoritative” style guides, like Elements of Style, by William Strunk and E.B. White. Liberman and Pullum delight in pointing out that traditional prescriptive grammar is riddled with bizarre rules that are known by thoughtful people to be baseless in English but live on like prescriptivist zombies to plague less-enlightened writers everywhere. There is no reason to always avoid splitting infinitives; Pullum notes that in the headline “New SAT writing section aims to better reflect needed skills,” the “to” cannot be moved without changing the meaning of the sentence or making it awkward. Yet the rule, which should have vanished long ago, is enforced today at the Economist, where I work. (Our style book notes that “the ban is pointless. Unfortunately, to see it broken would be annoying to so many people that you should observe it.”) Similarly, there is no reason not to end a sentence with a preposition—the best writers have done it in English for centuries—but most educated adults have been taught this rule at least once and still try to observe it in formal writing. To follow such rules, simply because they are rules, is to say “nothing is relevant.” Forget what every native English-speaker does and what the greatest writers ever to use English wrote. No evidence from centuries of actual usage is relevant. It’s a Rule. Look it up.

Pullum has special vitriol for Elements of Style, which he calls a “horrid little notebook of nonsense,” and debunks a number of Strunk and White’s dicta. Take, for example, their insistence on using “that” in restrictive clauses and “which” in nonrestrictive ones. (Say “The house that Jack built is nicer than the one I built,” but “The house, which Jack built, is white.”) If you substituted “which” for the “that” in the first example, the Elements of Style, Microsoft Word, and the Slate stylebook would flag your choice as an “error”—even though your point would be perfectly clear. Pullum argues that the prohibition is unnecessary. With the help of some electronic book searching, he shows that Lewis Carroll, Charles Dickens, Emily Bronte, Joseph Conrad, Herman Melville and, yes, E.B. White all use “which” with restrictive clauses—often. (White, for example, does so in the second paragraph of Stuart Little.) If great writers break a rule frequently and naturally in writing, everyone else follows suit in speech, and doing so creates no confusion, that rule is a waste of everyone’s time.

While Pullum savages, Liberman gently teases, and one of his targets is Slate’sBushisms column. “W is no Homer,” he admits, of the president’s linguistic challenges. But he notes that every word Bush utters is heard by millions of viewers alert for a syntactic slip-up. If any one of us had that kind of prominence and millions of enemies, he reasons, it would be simple sport to transcribe our sentences and find a few that would make us look like Bush-level boobs. Spoken English is filled with false starts, retracings, and sentences that don’t quite parse on paper but are perfectly understandable in natural conversation. (Liberman even used a 2004 blog post, reprinted in the book, to invite Jacob Weisberg, editor of Slateand keeper of the “Bushisms” feature, to dinner on Liberman’s dime, if he could tape-record their conversation and compile a list of Weisbergisms.)

The blog-as-book format is difficult at times—links are presented as sidebars, which works better in some cases than others. But the book is readable throughout. Many of the essays do not take sides in the “usage wars” but rather offer insight into various topics using the linguist’s tool kit. What is it, technically, that makes Dan Brown’s writing so predictably plodding ? (He begins three books with nearly the exact same oddly phrased sentence, describing almost the exact same scene.) How many words for snow do Eskimos really have? (Maybe a couple more than we do.) What on earth is Hmoob ? (A language you may have heard of under another name.)

Despite the appeal of Madding Gerund, we surely haven’t heard the last of the prescriptivists—language remains an ever-popular subject of hell-in-a-handbasket complaints. John Dryden was criticizing Ben Jonson’s sentence-ending prepositions in 1672, and we may well be hearing similar complaints 300 years from now. Descriptivists like Steven Pinker and John McWhorter have made a stab at the popular case for thinking about language like a linguist, but only briefly in works on other subjects, and the likes of Safire and Truss still hold the field in the popular imagination. With Madding Gerund and Language Log, descriptivists have finally found articulate, entertaining, and often acerbic champions to reply.