I DON'T KNOW what ails the boy, Judge," an old joke went, "I've taught him everything I know and he's still an ignoramus." The same perplexing relationship seems to exist between educational reformers and America's public schools. For the past 70 years social planners and teachers-college theorists have been subjecting them to enlightened improvements. But despite open classrooms, a course choice wide enough to include things like marriage simulation and astrology, lenient marking, the absence of discipline, the presence of a powerful teachers' union, federal aid to local schools, and a Department of Education down here in Washington, the beneficiary is in deep trouble. For the past two decades, as everyone knows, schools have steadily declined in the skills and the learning they impart.

When questioned about that, educationists tended to claim that test scores were not really dropping and were, in any case, misleading and culturally biased. The usual suspects were rounded up: the Vietnam War, drugs, television, the temporary influx of minorities previously deprived of adequate schooling. But the war finally faded away and the population of recently integrated schools settled down -- yet the scores still fell. Until a day came when even liberal apologists began to concede that whatever baneful forces are loose in society, actual learning in school just might depend on such things as teaching a few serious substantive subjects, being able to maintain order and holding students to standards.

Small hopeful signs are all about us now: the blizzard of reports and recommendations for something that resembles a core curriculum in high schools; the 40 states trying minimal achievement tests for grade promotion; and the sprinkling of school systems that have dared establish a C average as a prerequisite for football and other extra-curricular activities; the rise of tests to help establish minimal teacher knowledge of the subject taught. But as Diane Ravitch points out in this fine collection of essays, such things represent only a slight swing of the pendulum. The American public has rarely shown more than sporadic interest in education. There is no consensus about what education can fairly be expected to do. Besides, she warns, the conflicting presumptions about society and learning that have helped bring us to our present pedagogical pickle are highly politicized and still very much in place.

Given the thrust toward cultural pluralism, Ravitch does not think the situation is likely to change soon. Her book is not an attempt to reach consensus or even, mainly, to lobby for specific programs or cast blame. Instead with penetrating questions, she submits hot educational issues to the cool perspectives of history, critically inquiring as to how things happened, and suggesting what we can reasonably expect from the fads and fancies that have already been tried.

MANY OF her topics are fairly predictable: tax tuition credits (not dangerous but not a very good idea, either); changing fashions in education (they are a plague); the uses and misuses of tests; the history of minority group education in the U.S. -- on which there seems to be a bit more consensus in argument than one might expect; the recent shift from color blind to color conscious (which shattered the consensus). The Schools We Deserve, rather than pedagogical in style, is a probing field guide to highly charged school issues, something that should be read by any parent or layman who wants to make sense of the current educational scene.

The heaviest critical attention lately has fallen upon the high schools. Ravitch notes, however, that colleges are to blame for lowering admission standards, thus sabotaging one of the most compelling arguments high schools have for maintaining a serious curriculum. Elementary shcools, too, have largely escaped attack because something like a consensus exists about what should be taught there. Yet it is there, Ravitch notes, that the debilitating emphasis on skills, rather than knowledge, a weakness for predigested rather than real books, first sets in. The great enemy of educaton, after all, is not discipline or work or ignorance, but boredom.

She worries about zealots with grandiose plans for transforming the overworked public schools into utopian Santa's workshops for remaking society. She deplores politicians who accept untested sociological theory as educational fact while laying all sorts of counterproductive requirements on the schools. Bilingual education, for instance, is now a civil right in some states. Perhaps it should be, but not on the grounds customarily used, i.e. that it helps foreign minorities be assimilated into mainstream learning faster -- which it doesn't. And she calls attention to the fact that apparently enlightened reforms often end by producing unexpected and baneful by-products. The most powerful teachers' union, for example, which for decades did great service to education, has been dead set against any attempt to test teachers even for bare minimum knowledge of their subject. The turn-of-the-century effort to make learning more practical for the needs of immigrant masses (many of whom, however, preferred harsh, traditional curriculum, because it hastened assimilation), not only led to broad curriculum, but to the current attacks on almost all traditional learning as elitist, racist and undemocratic.

Ravitch, out of Texas and Wellesley College, and now a professor of history at Columbia Teachers College, compellingly laments the loss of history at all levels of American education, partly because she thinks that a knowledge of history can help you avoid doing what American education has done a lot of -- trying to reinvent the wheel. Teachers should not be made scapegoats. They were, and still are, she feels, devoted and long-suffering folk who preserved much of value by ignoring the shifting fads in teaching theory, and by continuing to use old-fashioned means like examinations, grading, textbooks, the recitation method, courses that focus on discrete subjects -- because these things work in the classroom. However, teachers "must feel a sense of inadequacy, knowing that the techniques they find necessary for teaching have been condemned by progressive pedagogical experts for most of the century." With devastating mildness, Diane Ravitch concludes, "If so great a divergence between theory and practice existed in any other profession, it would most likely be considered a scandal."