If you want to achieve traction on nearly any issue, you have to make a case for an economic payoff.

Thus, climate change activists understand that just saving the world isn’t enough; green energy also has to create jobs and economic growth.

Thus, if you want to help the 14.7 million children who are growing up poor, it serves your cause to point out that, according to the Children’s Defense Fund, the $77 billion it would cost to reduce child poverty is much less than the $500 billion that poor children cost our nation every year.

And, thus, if you want to promote “school choice,” your first and most prominent means of attack depends on promoting the economic benefits of getting more students out of public schools and into private schools.

That’s what’s happening in Texas right now. A bill has been filed in the Texas Senate that would divert public funds to vouchers that could be used to pay for private schools.

But the issue is national. The Texas bill is cobbled together from conservative boilerplate supplied by the American Legislative Exchange Council in Arlington, Va. ALEC provides model bills suitable for sponsorship in every state.

In the Texas version of ALEC’s vision for American education, vouchers for 60 percent of Texas’ per-student expenditure would be issued to parents who wish to transfer their children out of public schools.

The case for school vouchers in Texas is made in a 43-page document commissioned by conservative interests. “The Texas Economy and School Choice” was produced by Arthur Laffer, who is often called the “father of supply-side economics.”

George H.W. Bush called this theory of taxation “voodoo economics,” and even though it’s been widely discredited, Laffer is influential in conservative circles.

Laffer’s report says that vouchers would increase the Texas GDP and standard of living by up to 30 percent, adding as much as $460 billion to the economy. New jobs could reach 985,000.

In short, even though his report admits that only 0.5 percent to 6 percent of public school students would enroll in a voucher program during its first two years, Laffer contends that the economic impact of school “choice” will be phenomenal. Even public school teachers will enjoy higher salaries.

But any report that sets out to support a predetermined principle — and that does it in such breathless terms — ought to be viewed with considerable skepticism. Although minority children figure prominently in Laffer’s four-color report — at least 19 of the 21 children featured in its photographs are African-American or Hispanic — the first and most obvious beneficiaries of a school voucher program would be the parents of children who are already in private schools, and the schools themselves. These are the people who want voucher programs most of all.

We know how to produce excellent public schools. The problem is that we’ve never been willing to produce them for everyone, regardless of race or economic status.

Public education has provided a great American legacy, one that has tended to bring us together rather than separate us. We shouldn’t allow that legacy to be undone by ideology.