Libertarians argue that, as no public school can satisfy the disparate needs and priorities of everyone in society, citizens should not be coerced to pay taxes to support public education. For example, your neighbor might object to paying taxes to support sex education classes. You might object to paying to have your children learn French but not Chinese. With private schooling, you pay for the education which is closest (among available options) to your values and priorities. Since a fundamental libertarian principle is that government should not coerce its citizens except to protect their rights, this inability to meet simultaneously the priorities of all taxpayers is sufficient justification in the libertarian view to junk the public school system.
Public education is the most important potential leveler of opportunity in our society. Each generation has the opportunity to obtain a solid education, with its attendant economic benefits. Closing down this path for economic advancement would fundamentally alter Americans' view of the wealthy. Most of us view wealth positively, in part, perhaps because we can easily imagine ourselves or our children acquiring wealth someday. At least once a week I give my children (albeit tongue in cheek) some duty I wish them to perform for me once they are `rich and famous.' The absence of public education would fundamentally alter our view of the fluidity of the socio-economic strata, leading to more class warfare than even Nancy Pelosi can gin up.
Of course our public schools have often failed to provide a decent education. Anyone who has ever homeschooled a child rapidly discovers that children can easily learn at double the rate at which they are taught in most schools (caveat: my children have only attended 4 of the N x 100,000 schools in the U.S; so I may have some sampling error here in my treatment of 'most'.) My children have had English teachers who don't know grammar and speak substandard English, geometry teachers who don't know geometry, and history teachers who don't know anything. They have also had many good teachers, but I still resent how much time the bad teachers have wasted. So, public education as an economic equalizer is an ideal which is not always realized.
Like most small government conservatives, I assume that private schools have the potential to provide a better education than public schools, especially in large school districts, which bring out the worst in the education bureaucracy and have the potential for the greatest variety of private options. I strongly support education vouchers. Economically, however, they only make sense if they are means tested. I would be willing to wager that most private school students have parents in the top 5-10 percent of wage earners. I agree with the libertarians here: why should the middle wage earners support via voucher or tax credit the education choices of the upper and upper middle class of wage earners? A much more interesting experiment would be initially to fund vouchers only for those below the poverty level. The vouchers should also fund an amount significantly less than the current cost of public education. This will test the claim that private education can be provided more cheaply and reduce the overall cost of education.
If private schools can provide both a better and a cheaper education, then vouchers would save money and eventually lead to the founding of many more private schools and the closing of many public schools. As private schools which are not targeted at the upper income levels proliferate, perhaps more people would choose to opt out of the public schools. As the public school system shrinks, perhaps it would reform itself to survive. If not, then a growing number of private school options targeted at lower and middle class students might lead so many people to opt out of the public schools, that we would achieve a variant of the libertarian school system : a system where all or most schools are private, but public funds ensure that the poor have access to an education of sufficiently high quality that each new generation has the opportunity to exit poverty.
Once the education for the poor is guaranteed, ensuring that children are not overly constrained by the sins of their fathers, my resistance to the libertarian argument against public education lessens, but I would like to see the effects of vouchers for the poor before revisiting the debate.