The German philosopher and sociologist Jürgen Habermas (born 1929) challenged social science by suggesting that despite appearances to the contrary, human beings are capable of rationality and under some conditions are able to communicate with one another successfully; the barriers preventing the exercise of reason and mutual understanding can be identified, comprehended, and reduced.

Jürgen Habermas was born in Düsseldorf, Germany, on June 18, 1929. He grew up in nearby Gummersbach, where his father was director of the local seminary. He was 16 when World War II ended. At that time he experienced a sense of revulsion with the Germans' "collectively realized inhumanity," which characterized, he believed, their lack of response to the revelations in the Nürenberg trials about the Nazi death machine. His own very different reaction, one of shock and horror, constituted what he described as "that first rupture, which still gapes...