Over the past few years, Latin American countries from Brazil to Bolivia to Costa Rica to Peru have been electing left-of-center leaders to fill their presidential palaces. That shift is but the latest move in a long-time cultural struggle pitting modernizers—who want Latin America to enhance its centuries-old attachment to Western culture—against reactionaries, who do all they can to resist that idea.

This tension is holding Latin America back, obstructing its political and economic development compared to other regions, such as East Asia and Central Europe, that just a few decades ago were similarly lagging behind. Indeed, over the past 30 years, every Latin American country except Chile—the epitome of a modernizer—has seen its per capita income fall as a proportion of U.S. per capita income. Meanwhile, regional surveys betray a profound dissatisfaction with democratic institutions and traditional parties.

Modernizers as well as reactionaries are scattered across the Latin American political landscape today, belying the simplistic left-right dichotomy. The modernizers include both the center-right and what some fellow writers and I call the vegetarian left; meanwhile, the reactionaries make up the carnivore left.

In the center-right, leaders such as the outgoing Vicente Fox of Mexico, Elías Antonio Saca of El Salvador and Alvaro Uribe of Colombia understand that the market economy and the rule of law are the foundations of prosperity. Leaving aside Uribe, who is absorbed by the war against narco-guerrillas, leaders on the center-right have largely chosen to preserve the status quo rather than reform it. They have maintained monetary discipline and tried to lure foreign investors. But they have done little to transform their countries’ key institutions, including the judiciary, or to incorporate the masses into the global economy.

The vegetarian left is represented by figures such as Luiz Inãcio Lula da Silva of Brazil, Tabaré Vázquez of Uruguay and Oscar Arias of Costa Rica. They have avoided the mistakes of the old left, including routine confrontation with the outside world and fiscal profligacy. But they have settled into a sort of bovine social-democratic placidity, unwilling to produce a truly modernizing élan. They have failed to reduce the bureaucracy, reform taxation or strengthen the rule of law.

Then there are the members of the carnivorous left, including Fidel and Raúl Castro of Cuba, Hugo Chávez of Venezuela and Evo Morales of Bolivia, as well as opposition movements in Mexico, Nicaragua and Ecuador. They cling to a Marxist view of society and a Cold War mentality; they seek to exploit ethnic tensions, particularly in the Andean region. Chávez’s oil is funding much of this effort.

Recent elections reflect the tensions among these groups. In Mexico, the legitimate victor in the presidential race, Felipe Calderón, is a center-right modernizer, but carnivore Andrés Manuel López Obrador is claiming electoral fraud. If Calderón is confirmed, it is unclear whether he will be an active modernizer—as he promises—or a passive one, like Fox. In Peru, new President Alan García presents himself as a modernizer in contrast to carnivore leftist Ollanta Humala, whom he barely defeated. But García was a carnivore during his first term in the 1980s; the burden is now on him to show that his political intestines have evolved from raw meat to vegetables.

At the heart of Latin America’s economic and social travails is the prevalence of populism, which has allowed the development of two-tiered societies in which the privileged obtain state support while the rest face labyrinthine obstacles. Led by 20th-century strongmen who blamed rich nations for Latin America’s plight, populism produced stifling bureaucracies, judicial subservience to political authorities and parasitical economies. Indeed, populism is so ingrained in the Latin American psyche that it still dominates institutions even when modernizers reach power. That is why the 1990s—a period of considerable privatization and market opening in Latin America—ended in frustration and the reemergence of powerful populist movements.

Yet, without strong and impartial institutions, capitalism becomes pseudocapitalism. Without the rule of law, the current populist resurgence—led by the carnivore leftists—will foster further resistance to change. For modernizers to defeat the reactionaries, Latin America must break the populist complex once and for all.