Once you get beyond the yes-I-can-no-you-can’t debate over whether Republican Sam Katz could lower the city wage tax to 4 percent without crippling services, the truth is this: There is no way to know for sure. No way to see the future, to tell whether Katz is simply wooing voters with a politician’s pitch of lower taxes or whether he really could take less of their money and still adequately police their neighborhoods, pick up their trash, plow their streets.

No way to know whether Katz’s plan a textbook tome titled, Reducing the Cost of Living and Doing Business in Philadelphia, is campaign legerdemain or a better mousetrap.

Unless, of course, he becomes the next mayor.

With his wage-tax plan, Katz is asking for more trust than the usual dose. It is based on concepts -- “strategic planning and performance measurement,” “objective goals and quantifiable outcomes,” “activity-based costing” -- not details.

It seeks to use incentives to get employees to work harder and smarter -- because they want to. It would have government not simply propose spending but define "missions, place new focus on value and efficiency, and compare government services to the private sector."

All this, according to Katz, would have the net effect of making government work better and eliminate waste. He can’t pinpoint where that waste is, he said, until his management system is put into place.

“High taxes are chasing business and residents out of Philadelphia and are discouraging others from coming here,” Katz said. “Staying the course simply won’t cut it.”

Democratic nominee John F. Street, too, wants to reduce the wage tax, for city residents from 4.61 percent to 4.46 percent by 2004, and for commuters from 4.01 percent to 3.88 percent. Katz would lower the tax to 4 percent for both, a savings of $244 yearly for city residents.

Katz’s plan would save a city resident earning $40,000 a year $244 in 2004; Street’s cut would produce a $60 annual tax savings.

The wage tax accounts for about $900 million in annual tax revenues, about half of all city tax revenues. State and federal aid boosts the city budget to about $2.7 billion.

Katz portrays himself as an imaginative incoming chief executive who wants to reinvent and reengineer government -- to borrow a phrase from his 83-page plan -- and Street as the system-produced pol who can’t see past the same-old-same-old ways of government. It couldn’t hurt, Katz says, to look at things a different way.

Pie in the sky, responds Street, who depicts Katz as a dreamy schoolboy who has never gotten his hands dirty in the real world of government. His plan is seen as akin to a college term paper, which might be fine for the classroom but which would never work in City Hall.

But Katz says he is hardly an amateur. He has made a career out of advising cities and states on government finances, operated a successful business, and studied how other municipalities have cut spending.

“As to budget numbers and figuring out the technical part of it -- that’s the same everywhere,’’ said Bob Barnett, Katz’s campaign director. “What he’s done in other places is applicable here.’’

Street contends that there is only one reason Katz can keep a straight face and promise to run government “2 percent cheaper and 2 percent better” -- because he’s never tried to do it. Street has cut costs during his 19 years as a member and then president of City Council.

“Two percent’s a lot of money. … It’s not an easy thing to do,” says F. John White, Katz’s former partner at Public Financial Management and the author -- “along with Ed Rendell and John Street” -- of the city’s current five-year plan, which proposes the more modest reductions in the wage tax.

“I do think it’s overly simplistic to say, ‘I’m going to wring 2 percent out of city government, that everyone knows there’s 2 percent waste in city government,’ ” said White, a Street supporter. “Well, where is it? If you know, show where it is.”

Katz’s plan “has not one specific suggestion about how to save a nickel,” said David L. Cohen, who attended Street’s news conference on Friday to rebut the Katz plan. Cohen left as Rendell’s chief of staff in 1997 and is now a lawyer in private practice and a Street supporter.

“Voodoo economics,” said State Rep. Dwight Evans, ranking Democrat on the House Appropriations Committee. Evans, who lost to Street in the mayoral primary and who now supports him, predicted that Katz’s proposal to equalize the wage tax for city residents and nonresidents would result in revenge among suburban legislators in Harrisburg.

Nonresidents now pay 4.01 percent. Street proposes reducing that to 3.88 percent.

Stephen MacNettcq, a spokesman for Senate Majority Leader F. Joseph Loeper Jr. (R., Del.), said Loeper would “prefer” to have equal tax reductions for city and suburban residents but that not reducing the nonresident wage tax would “not create a crisis in legislative relations” with the city.

Street said that many big-ticket budget items can’t be cut, things like police and firefighters, money for courts and prisons, and funding for child welfare and mental health; for the last two, the city receives matching state and federal funding, respectively.

Other reductions are difficult at best, Street said.

“I remember it like it was yesterday,” he said of seeking budget trims in the 1980s. “I had all this stuff in front of me and I was saying, ‘Where can we go?’ And, one at a time, we realized: You can’t cut libraries. You can’t cut parks. You can’t cut the courts. You can’t cut debt service.”

Street said, however, that he would find more reductions if he’s elected mayor. He hasn’t said where, either. Then again, Street does not propose nearly as big a reduction as Katz does.

Street said Katz would not only have to realize his estimated saving of $245.5 million by 2004 to chop the wage tax to 4 percent, but at least $500 million once “contingencies” -- a new contract for city workers, increased medical costs -- are taken into account.

Said Street, “We are going to use the tried and tested management techniques that we have been using in the last seven years to do this.”

To Katz, those are simply old methods, and they’re not good enough to stem the loss of people and jobs from Philadelphia.

Barnett labeled Street the candidate of the status quo, who has “no creativity. There’s no vision.” Katz has both, he said.

Katz intends to apply private business techniques to government and study what other cities have done to operate more cheaply. His plan points to Indianapolis and Milwaukee, where changes have produced slimmer governments and lower taxes.

He cites examples of how waste was found in those Midwestern cities: In one case, $252,000 was spent on repairs for a garbage truck over four years, when a new one would have cost $90,000.

In Milwaukee, the city budget grows more slowly than inflation, meaning that city spending has gone down since 1988, according to Jeff Fleming, spokesman for Mayor John Norquist.

Milwaukee did that by cutting jobs, shaving some services, and reducing worker benefits: There are 700 fewer employees than in 1988. Garbage collectors stopped going into people’s backyards; residents now must cart their trash to the street. City workers get basic health maintenance organization coverage and have to pay for any extras themselves.

When it comes to government costs, Milwaukee is different from Philadelphia in an important way -- it is not a county. That means that, unlike Philadelphia, it is not responsible for a variety of costs, including those of many courts, prisons and welfare.

In Indianapolis, which has a far smaller budget and less poverty than Philadelphia, officials have slashed the budget by 18 percent in inflation-adjusted dollars since 1992. Since then, the city workforce has been cut by 27 percent, to 3,386, through privatization, attrition and management layoffs, according to the Indianapolis mayor’s office.

Katz doesn’t know yet where some of his projected savings will come from because the city workforce is going to help him find them.

His plan touts an Indianapolis program called Hot Idea$ in which employees can earn as much as $3,000 for money-saving ideas. Worker groups that bring costs down more than projections would get to keep part of the extra saving as part of an “incentive pay” program.

“Milwaukee and Indianapolis have turned the standard operating procedure of city government on its head,” the Katz plan states. And though Philadelphia has made “laudable and significant progress,” becoming more efficient in certain areas, “now is the time to go much further and much faster.’’

Trust him, Katz says, it can be done.