One aspect of the education debate in the mayoral campaign has gotten far too little attention, and it is this:

John Street's position is mostly bunk.

Let's start with Street's contention, made in ads and repeated in his stump speech, that tuition vouchers, which Sam Katz is willing to try, would "rob the public schools of desperately needed resources."

Exactly the opposite is the case. The voucher pilot program proposed by Gov. Ridge earlier this year provided that school districts involved continue to get state funds for at least five years based on the number of students enrolled before the program started no matter how many students took vouchers and left.

The net result, as a state Education Department spokesman summed it up this week, would be "more money for fewer kids."

Now, from a theorist's point of view this is bad policy. If kids leave, the schools in question should get less money, to prod them into improving. But political realities being what they are, any voucher program is sure to contain this "hold harmless" provision.

Next, Street says that he will get more money for the city schools by "precipitating a crisis" and negotiating an increase in the ensuing chaos.

But there will be no chaos. There is no mystery about what the state government will do: It will take over the city schools. The legislation for this has already been enacted, and, not incidentally, empowers the state-appointed executive to do most of the other things Street is attacking Katz for advocating, such as contracting with school management companies to operate city schools. (Indeed, a cynic could argue that the quickest way to bring about real school reform in Philadelphia would be to elect Street and have him "precipitate a crisis.")

Note, too, that the Philadelphia school district already intends to have a private company run a special school for disruptive students, so the issue of whether the district should purchase such services is moot.

As for Street's claim that he can convince legislators to give more money to the city schools, here is what will happen to him if he tries: They will laugh.

As every legislator knows - even if no one in Philadelphia admits it - the city already gets more than its share of state money. Its per-pupil expenditure is comparatively low because the city's contribution is so paltry. Of the 24 municipalities in Pennsylvania, Philadelphia ranks last, proportionally, in education spending.

School choice is no longer a novel concept. Most industrialized democracies have used it for years, and a number of school-choice experiments are underway in America. If there are questions here, there are often answers elsewhere.

When Milwaukee started its school- choice experiment, for instance, there were similar shouts of alarm that this would take money from the public schools. So did it? Absolutely not. State aid rose 55 percent, in constant dollars, during the 10 years the choice program has been in effect.

And there is now clear evidence that students taking the vouchers make achievement gains.

The claim that voucher programs will "cream" the best students from the public schools was shot down by a study of a San Antonio school district in which businessmen made vouchers available to any family that wanted them. The students who took the vouchers turned out to be a cross-section of the district's students.

A newly enacted program in Florida, already providing vouchers to kids in failing schools, is demonstrating that public school districts will respond well. Gov. Jeb Bush recently testified to Congress that "it's been fun" watching public school superintendents scramble to be sure no more of their schools get an F.

Street, of course, is attacking vouchers as a political ploy. White liberals supposedly hold the key to the election, and are thought to be anti-voucher. In Philadelphia they tend to be mostly Old Lefties, whose kids long ago finished up at Germantown Friends - or maybe Central - and moved to Silicon Valley.

But there's evidence that liberals are shifting on this issue. The New Republic, the most influential left-of-center opinion journal in the country, recently editorialized in favor of vouchers for disadvantaged students. The same issue contained an article titled "A Liberal Case for Vouchers" by Harvard professor Paul Peterson, and John Street, for one, ought to read it.