Teachers these days are confused by the high volume of attacks on the profession. Members of teachers’ unions are beset by the frequent, virulent attacks on the very idea of collective bargaining.

In conservative states, governors and legislatures are doing whatever they can to weaken or eliminate collective bargaining. Two Hollywood movies in the past two years have cast the unions as the evil force that protects incompetent, lazy teachers and causes poor children to get low test scores. Without unions, it seems, our test scores would be the highest in the world and probably there would be no poverty either. All the industries that fled to China because of labor unions would have stayed here and there would be full employment for anyone willing to work for $2 an hour and live in a dormitory near the factory.

Now comes a publication from the conservative think tank Thomas B. Fordham Institute of DC and Dayton showing just how powerful those evil unions are.

Its report purports to prove that there is no association between high levels of union membership and academic achievement. Massachusetts may be number 1 in academic achievement (93% unionized), followed at the top of NAEP by New Jersey (97%) and Connecticut (99%), but TBF has devised a different way to parse those figures and conclude that unions are actually an obstacle to high achievement.

Mike Petrilli of TBF claims that I am one of those people who say that unions “can’t possibly be to blame for lackluster student achievement…if anything, unionization helps raise achievement, they say.”

This is a falsehood, misinformation, or willful ignorance. Petrilli is annoyed because I pointed out on this blog that Romney boasts about the academic gains in Massachusetts at the same time he is determined to flatten teachers’ unions, never acknowledging that those remarkable gains were accomplished by unionized teachers.

Petrilli should read my book.

I never wrote that unions cause higher achievement. DC is unionized and has low achievement, but it is not because it has a union. Student performance on NAEP is very low for Mississippi and Louisiana is very low, but it is not because they have weak unions.

What I wrote in “The Death and Life of the Great American School System” is this: “No one, to my knowledge, has demonstrated a clear, indisputable correlation between teacher unionism and academic achievement, either negative or positive. The Southern states, where teachers’ unions have historically been either weak or nonexistent, have always had the poorest student performance on national examinations. Massachusetts, the state with the highest academic performance, has long had strong teachers’ unions. The difference in performance is probably due to economics, not to unionization. Where there are affluent communities, student performance tends to be higher, whether or not their teachers belong to unions.”

What the unions do is to give teachers a voice in decisions about the conditions of teaching and learning. They give them representation if they are treated unjustly. They guarantee due process. Further, they provide an advocate for public education when decisions are made about the budget. Had there been a strong union in Texas, the Legislature would not have cut $5.4 billion from the budget for public education. Had there been a strong union in Louisiana, the Legislature would not have authorized the creation of vouchers and charters that take money out of the minimum foundation budget for public schools.

And unions do something else that matters to our society: They create a middle class. It may not be a coincidence that income inequality has grown as union membership has declined. Norman Hill and Velma Hill, veteran civil rights and labor activists, pointed out in a recent post on the Shanker blog that “the wages of black union members are 31 percent higher than the wages of African Americans who are not union members. The union wage advantage for women workers is 34 percent; for Latino workers, it is a whopping 51 percent.”

Rightwing ideologues like ALEC and like-minded think tanks across the nation want a union-free America, free to drive down wages and increase the working hours of teachers and other workers. If they had their way, teachers would have alternate certification or none at all; would be at-will employees; would serve at the pleasure of the corporation that hired them; would leave teaching as easily as they entered it; and would have nothing to say about working conditions or pay or hours.

This would predictably destroy the teaching profession. Why anyone thinks it would improve education is beyond my understanding.