Augusto Starita / Ministerio de Cultura de la Nación · CC BY-SA 2.0

Rewrote linguistics before he turned thirty: Syntactic Structures (1957) argued that humans are born with an innate grammar underlying every language, a claim that displaced behaviorist theories of how children learn to speak and helped found cognitive science as a field. He has spent the decades since as one of the most cited scholars alive, working simultaneously as an MIT linguistics professor and a relentless critic of American foreign policy — two careers he has kept running in parallel for over sixty years.