O NE OF THE most effective soft-power programmes ever was launched in 1955 by the American government. Over the next 18 years, it sent over 100 Chilean students to Chicago University to study economics under Milton Friedman. The ideas those students absorbed were regarded as outlandish in their increasingly socialist country until Augusto Pinochet, brought to power by a coup in 1973, put them into practice. Among other things, he turned the entire education system into a voucher scheme.

The Chilean experiment is unique in its scale but not its nature. In education, public-private partnerships of various kinds abound. At tertiary level, governments provide or guarantee loans for students to spend at private colleges. At primary and secondary level, they include charters, academies and vouchers.

The Netherlands, perhaps surprisingly, runs much of its education system as a public-private partnership, because religious divisions meant that in the past parents did not trust the state to run schools. Its schools are publicly financed, not for profit, non-selective and close to free, but they enjoy a lot of autonomy. It works: education in the Netherlands is among the best in the world.

The desire to liberate schools from the state—and the teachers’ unions—also lies behind the growth of the charter movement in America, and academies and “free schools” in Britain. America’s charters started in Minnesota in 1992 and spread state by state; Britain’s academies were conceived by a centrist Labour government in 2000. Both are publicly funded and privately run. Enrolment in charters rose from 400,000 in 2000 to 2.8m in 2015. Nearly three-quarters of British secondary-school pupils and one-third of primary-school pupils attend academies or free schools.

In developing countries public-private partnerships are driven largely by the desire to maximise enrolment and minimise inequality. India’s government decreed in 2009 that 25% of places in private schools should be reserved for “economically weaker sections” who would be paid for by each state government. Colombia, Venezuela, Peru, Sierra Leone, Uganda, India, Pakistan and the Philippines now have voucher, charter or other sorts of subsidy schemes, but Chile’s is the only national-scale experiment.

Chile has three sorts of schools: entirely private (which charge whatever fees they like and get no money from the government); private voucher-financed; and public schools. The children of the elite attend the first lot; both middle- and working-class families are gravitating towards the second (see chart).

Those who run Chile’s private-voucher schools attribute their success to their autonomy. “We’ve introduced a Singaporean system for teaching maths in a more practical way that required us to buy special materials,” says Marianela Cisternas of Belén Educa, a Catholic foundation that runs 12 schools. “A municipal school could not have done that.” Principals also have more freedom to hire and fire staff. Jessica Vergara, principal of Colegio Rosa Elvira Matte de Prieto, a school in Lo Espejo, a rough area of southern Santiago, has fired 18 teachers in five years. In a municipal school, she says, she would not have been able to.

Pupils at voucher schools do only a little better than those at municipal schools after allowing for their socioeconomic background. But that, says Harald Beyer, a former minister of education in Chile, is beside the point: competition has improved the municipal schools’ performance too. Academic studies cast doubt on whether competition has really improved outcomes, yet even sceptics see virtues in the system. Emiliana Vegas of the Inter-American Development Bank reckons that the main driver of improvement has been the rich data produced by the system, which allow the state to keep tabs on how it is doing.

Chile’s educational performance, though far from stellar, is good by local standards. The country does better in reading (see chart), maths and science than the other Latin American countries for which the OECD , a club of mostly rich countries, collects data. It also spends less as a share of GDP .

But the left is uncomfortable with competition, which it feels can increase inequality in an already unequal country. Schoolchildren protested against inequality in education in 2006, university students in 2011. Michelle Bachelet, a former Chilean president, shifted the system leftwards, first making vouchers income-related and subsequently banning profits, fees and selection in voucher schools. These changes are being implemented gradually.

Supporters of the changes argue that credit for the improvement in standards should go mainly to the investments in the curriculum, teacher training and assessment in the 1990s, and that more state intervention will improve it further. “We now have a system that has a better chance of producing the combination of quality and equity that society needs,” says Cristian Cox Donoso of the Diego Portales University. Chile’s system, as Gregory Elacqua of the Inter-American Development Bank points out, is starting to look rather like the Netherlands’. But critics worry that the changes are undermining its virtues. Mr Beyer thinks banning fees and profits will discourage investment and innovation. Victor Gerardo, principal of the Liceo San Pedro Poveda, one of the best private voucher schools, says that without top-up fees his school will be “kaputt”. Mariana Aylwin, a former education minister whose foundation runs two schools, is concerned about the bureaucracy that inevitably comes with increasing government oversight. “With so many obligations and controls, schools are losing their autonomy and wasting time.” Ms Vergara reckons that she spends as much as half her working hours dealing with government paperwork.

But the most contentious issue is selection. Its abolition, intended to increase social integration, has been exceedingly unpopular. “Families are in favour of segregation,” says Dante Contreras, an economist at the University of Chile. “They want to be segregated from poorer people.” Liliana Ramírez, who is head of the parents’ association at the Lo Espejo school, says that because selection has stopped, “there are lots of people in the school who shouldn’t be here. People who don’t do honest work, who take drugs or deal in drugs.” But this is not a problem for the elite, which, on both left and right, sends its children to the 9% of schools that are entirely private.

The selection issue seems to have tipped the polls against Ms Bachelet. Her coalition lost power at the end of 2017 and she was replaced (for the second time) by Sebastián Piñera, who is trying to reintroduce a limited form of selection. But through all the arguments over its education system, not even the left suggested binning the voucher system. By and large, Chileans accept that it has worked.

Charged as they are by the memory of military dictatorship, Chile’s arguments over the politics of education are especially intense, but there are similar tensions between individual freedom and collective values all over the world. In many countries, as in China, government is reacting to the growth of the private sector by tightening regulations. Last June Dubai imposed a freeze on school fees, and last December Pakistan’s Supreme Court decreed that schools charging more than 5,000 rupees a month must cut their fees by 20%. “A lot of schools will shut down if this isn’t rescinded,” says Kasim Kasuri, chief executive of Beaconhouse School System. Several Indian states have also introduced controls on fees, and closed down some private schools on the ground that they did not meet standards set by the Right to Education Act—even though only 8% of government schools comply with them. Bureaucrats use those standards to extract bribes. “To get your school recognised,” says Mr Dhankar at Hari Vidya Bhawan School in Delhi, “you have to pay for the proper infrastructure, you have to pay five lakh ($7,250) bribes on top of that, and then they’re expecting some other gifts at festivals.”

Behind the tightening regulations lies a suspicion widespread among governments: that the growth of the private sector is bad for society. That view is not generally shared by parents.