Cuba’s supposed educational triumph is better understood as a product of propaganda and statistical chicanery.

Last month, on 60 Minutes, in a moment that starkly illustrated his worldview, Bernie Sanders repeated his longstanding admiration for Communist Cuba’s education achievements. Though he conceded that Fidel Castro’s “authoritarian” mode wasn’t ideal, he added, “You know, it’s unfair to simply say everything is bad. When Fidel Castro came into office, you know what he did? He had a massive literacy program. Is that a bad thing?” And it wasn’t just 60 Minutes. In recent weeks, Sanders defended the comments in a CNN town hall and during a Democratic presidential debate.

Sanders’s defense of Castro was roundly condemned. New Jersey Democratic senator Robert Menendez thundered, “I’m sure all of those who died at Castro’s hands and were shot at firing squads, all those who were tortured, those who live in my state and suffered enormously under the regime, the more than a million people who fled, I’m sure they all think that the literacy program was worth all of that.”

But the responses were so focused on Sanders’s moral obtuseness that they often left his point about the purported merits of the literacy program unchallenged. This is a mistake. For the evidence that Castro’s program, launched in 1961, drove big increases in Cuban literacy is dubious. Cuba’s supposed educational triumph is better understood as a product of propaganda and statistical chicanery.

In 1977, at the height of the Castro regime, a congressional delegation visited Cuba. Impressed by what Cuban officials told them, the delegation reported that the literacy rate under Castro had risen from 25 percent to 99 percent. This claim then took on a life of its own, irrespective of reality. In fact, in 1950, nine years before Castro seized power, Cuba already had one of the highest literacy rates in Latin America and the Caribbean: 78 percent, according to Oxford’s Latin American economic history database.

Indeed, Cuba’s reported literacy gains aren’t especially impressive in context. Many other nations in Latin America and the Caribbean increased their rates by similar (or larger) amounts over the same period. Castro seized power in 1959. In the following decades, Cuba reported reaching and then sustaining a literacy rate of 98 to 99 percent, a 20 percent increase. But economists at Oxford University’s Our World In Data project (using a compilation of Oxford, World Bank, and UNESCO resources) calculated that, during that same 50-year period (1960–2010), Bolivia’s literacy rate increased by 48 percent (from 44 to 92 percent); Brazil’s by 31 (from 60 to 91 percent); Colombia’s by 24 (from 70 to 94 percent); and Paraguay’s by 21 (from 73 to 94 percent). As of 2011, the median reported literacy rate for Latin American and the Caribbean was 93 percent.

There’s also legitimate reason to be skeptical of Cuba’s reported rates. As Max Roser and Esteban Ortiz-Ospina, researchers for the Our World In Data project, have noted, countries often self-report literacy data. That is the case with Cuba’s data, which come from its national census, in which the head of household provides its literacy status. One’s faith in Cuba’s metrics depends on how much one trusts citizens to provide a totalitarian regime with inconvenient information and Cuban officials to report inconvenient results.

Moreover, a 2008 UNESCO report noted that “conventional assessment methods usually overstate actual literacy levels.” The report added that across 20 nations, a “significant proportion of the adult population, although formally literate . . . had relatively weak literacy and numeracy skills.” So even if one accepts Cuban numbers (which is a stretch), simple claims of “literacy” can be misleading.

Finally, it’s well worth recognizing that Castro sought not just to promote literacy, but to have students imbibe revolutionary dogma. In 1961, Castro commissioned a literacy brigade with 300,000 teachers and student volunteers from across the country. He also began closing all private schools, an odd choice for a literacy program. But Castro didn’t trust private schools (many of them Catholic) to promote revolution adequately. The school day begins, after all, with students chanting “pioneers of Communism, we will be like Che.” And as Castro famously explained, “The universities are only available to those who share my revolutionary beliefs.” In 2003, Education Week reported that little had changed over the decades; students feared being ostracized or denied university admission if they didn’t partake in “pro-revolutionary” activities. Teachers who questioned such activities “paid a price for their opposition — from losing their teaching jobs to being jailed.”

Like data on Chinese economic growth or North Korean voting rates, Cuban literacy-rate data are only compelling to those inclined to believe authoritarian regimes. The problem with Sanders is not only that he seems morally obtuse about Castro’s means, but also that the ends he excuses weren’t great, either.