The emergence of previously unknown artwork said to be made by the popular Mexican artist Frida Kahlo (1907-54) has led to a very public debate about its authenticity. In Mexico, Kahlo is officially ranked an artist of the national patrimony, a formal endorsement foreign to American culture. Without official backing, an archive of previously unknown material faces high hurdles for acceptance. Aggressive bullying over the discovery by Kahlo-establishment figures is so strange that it suggests something bigger...