Sergio Malbergier writes (“E a estupidez, estupido!,” Folha de S. Paulo, September 11) about what marks, according to him, the current Brazilian presidential campaign: The utter ignorance of the voters. Malbergier believes that candidates and their marketers are so convinced of the electorate’s stupidity (Malbergier does not seem willing to differentiate between stupidity and ignorance) that they will always…