WE HAVE a mother tongue as stubborn and contrary

as a mule. It prefers to follow trails of its own choosing and to travel at its own gait, seemingly oblivious to the giddyaps, whoas, gees, and haws of would-be drivers.

Is it really so oblivious? Yes indeed, insists Professor X; attempts to interfere with the language, whether to reform it or to save it from going astray, are impertinent and futile, if not downright immoral. Not at all, counters Columnist Y; it is our bounden duty to bring the mule's judgments into line with our own, even if that requires beating the beast between the ears with a two-by-four to gain its attention. Though this endless dispute may not affect the course of the language, surely it improves the health of the disputants by stirring up their tired blood.

One good way to measure the adaptability of American English is to look at the new words that emerge to keep up with changing times. By this rule of thumb the language is in fine shape. The number of made-in-America locutions described by Stuart Berg Flexner in Listening to America comes to 15,000 or more, and I assure you they have not hurt us a bit. This joyous compendium, filling 591 big, handsome pages (the illustrations are handsome, too) is perhaps a more revealing social history without trying than most other books in its field are on purpose. Not only does Flexner expose us to wonderful words ("hot dog," "beauty contest," "as easy as pie," "ripsnorter," "dishing the dirt," "we was robbed"), but he reveals their origins, their meanings, and their often amazing ups and downs. As he says in the introduction, here are "the voices of the people, from Wall Street brokers, movie stars, advertising men, Phladelphia lawyers, and labor leaders through baseball and football players, golfers, boxers, smokers and drinkers, housewives, firemen, cab drivers, telephone operators, pirates, mailmen and waiters and waitresses to hippies, prostitutes, and the Mafia."

My bathroom scale puts the heft of Listening to America at a shade under five pounds. I would not have an ounce of that dieted away. It is a splendid book. You will have a lovely time reading it; you will make rich discoveries on every page; and you will find yourself relaying its delights to your friends for years to come.

The second of the two books considered here, Grammar and Good Taste, by Dennis E. Baron, marches to a more martial drummer. Professor Baron admires our language no end, but he believes it would be much better for all concerned if we would just leave it alone, or at least stop trying to imprint on others our own dubious notions of how it should be spoken and written. He goes back 200 years to review the generally unavailing attempts of our linguistic elite to alter the nation's verbal habits, or else to prevent the sort of language they approve of from being changed at all. His conclusion is that so-called rules of grammar are no more than ipse dixits -- personal opinions -- and that to continue imposing them is simply to burden new generations with an unnecessary sense of insecurity.

The reformers he cites include some notable figures in American history. In 1768, Benjamin Franklin developed an improved alphabet that he hoped would supersede the old, outdated one. In 1780, John Adams urged establishment of an official Academy to oversee the language. John Marshall pushed the same idea: "Were its only good the tendency it will have to preserve a sameness of language throughout our own wide spreading country," he wrote, "that alone would be an object worthy of the public attention."

Noah Webster campaigned indefatigably for simplified spelling. So did Mark Twain, who besides revived Franklin's dream of a more practical alphabet. Early in this century President Theodore Roosevelt officially directed the Government Printing Office to simplify the spelling of 300 common words. In 1934 the Chicago Tribune introduced into its pages about 80 phonetically spelled words, including fantom, hocky, crum, herse, and jaz.

These efforts came to nothing; the mule was not listening. Even the Tribune at last gave up; in 1975 it acknowledged defeat in an editorial entitled "Thru Is Through and So Is Tho." Professor Baron justly comments, "The early planners and reformers of American English . . . have left one common legacy for their twentieth-century counterparts to ponder: an overwhelming lack of success."

His remark, however, appears less justified for the preservers than for the reformers. Mingled with his lists of locutions that became respectable despite the tutting of grammarians are others that did not -- among them such dialecticisms as akst for asked, natur for nature, fortin for fortune, yarbs for herbs, taters for potatoes, chimbley for chimney, bile for boil. Sometimes, in fact, the purists gave up too easily. Webster felt forced to accept "You was" because educated speakers were saying it, but "you was" is no more. He approved of double negatives, but the double negative exists today only among the verbally deprived. Scores of usages that were controversial in Webster's day -- among them disinterested for uninterested and hopefully for hope -- still raise eyebrows after more than a hundred years. The old grammarians may not deserve most of the credit, or blame, for this, but at least they were not always on the losing side.

We are told that though English ignores human commands it is altering basically in response to seismic sociallchanges. It is true that modifications in the language, and not always for the worse, are continuous, as Flexner's 15,000 marvelous Americanisms confirm; but these modifications operate at the edge, not the center. Except at that edge, the language is perhaps more conservative today than ever before.

Two hundred years after the death of Chaucer in 1400, most literate people could read him only in translation. Yet nearly 400 years after the death of Shakespeare in 1616, Shakespeare is accessible with the help of an occasional footnote. Samuel Johnson, whose great dictionary appeared in 1755, would find little amiss with the diction of Dennis Baron, who is writing at the tag end of the 20th century. The invention of printing, the spread of literacy, and the increasing exposure of once- isolated areas to a dominant dialect have slowed change to a crawl.

The ages-old struggle between a misread past and an uncertain future will continue among language scholars, but language itself is not at stake; the problem is sociological, not linguistic. What is at stake is the irreplaceable potential of a whole new generation of young people, too often threatened by lack of common-sense training in the language they have no choice but to speak.

The too common contention that helping people to use English effectively is bound to damage their egos and weaken their sense of security is perhaps shorthand for a larger proposition: that in these emancipated times restraints, or even guidance, are an intolerable affront to the human spirit; our most fundamental right is the right to do our own thing.

It is a dubious doctrine. The sense of insecurity that a student may experience from failing an examination in English is small beer beside the lifelong insecurity that is the certain fate of incoherent nincompoops in an unforgiving world.