The showdown in Wisconsin over fringe benefits for public employees boils down to one number: 74.2. That's how many cents the public pays Milwaukee public-school teachers and other employees for retirement and health benefits for every dollar they receive in salary. The corresponding rate for employees of private firms is 24.3 cents.

Gov. Scott Walker's proposal would bring public-employee benefits closer in line with those of workers in the private sector. And to prevent benefits from reaching sky-high levels in the future,...