How do you teach teachers?

FORTUNE -- How do you go about teaching teachers how to teach? David K. Cohen's Teaching and Its Predicaments takes on that paradox. While the book's prescriptions are often too general -- teachers must show empathy and resolve, and communities should provide backup -- its descriptions of the task facing teachers are superb. Cohen, 77, a professor of education and public policy at the University of Michigan, compares teachers to other "human improvers" like psychotherapists and pastors. For these professionals, Cohen says, expertise isn't enough. Nor are good intentions -- or else more charter schools would succeed.

The core of the pedagogical predicament, according to Cohen, is that teachers (and other improvers) "depend on clients." By contrast, surgeons can do their job regardless of the patient's engagement. Moreover, surgeons aren't looking to turn patients into "apprentice surgeons," nor are salespersons trying to improve customers' ability to sell vacuum cleaners. Teachers, however, succeed only "if they help students acquire some elements of their own special expertise." Since students are a product of social and economic forces outside the classroom, it's a remarkable burden to demand quick results from teachers. Aren't we asking them to perform what we don't even expect from doctors? If you're fat and lethargic when you go see the cardiologist, chances are she can't work magic on you.

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Teaching and its discontents have long been hotly debated. Yet Cohen says reforms won't succeed until the art of teaching is transformed "from a largely routine and unimaginative practice into an intellectually ambitious and adventurous enterprise." He says it takes more than a common curriculum and tests. The problem is that, like other reformers, he doesn't much know what else to do. It's pie-in-the-sky for him to cry out for more dedicated teachers.

Perhaps he should have stepped down from the ivory tower and addressed concrete issues. He praises the efforts of Teach for America to recruit smart recent college graduates into urban teaching ranks. But he suggests no ideas on how to retain more of those recruits, who too often burn out. Nor does Cohen really address the structural problem of certification. Most school districts still require the formal credential of a master's degree in education, even though there are many mid-career professionals in a poor economy who represent a fresh talent pool. Programs like NYC Teaching Fellows may reduce the barriers to entry by streamlining the certification process, but they're the exception.

Cohen concludes that improved teaching "is more likely to be a long march than the quick fix that most recent reforms envision." That surely paints a bleak picture. Nonetheless, his book offers a thoughtful account of the challenge. You can't begin to fix what you don't understand.

This article is from the October 17, 2011 issue of Fortune.