Last fall, young people gathered in protest at dozens of universities across the country. Students of color spoke about feeling unwelcome or invisible, of being stereotyped, slighted, excluded, harassed. One deceptively simple phrase, derided or endorsed, seemed to crystallize what was at stake: “safe space.” The expression — which dates to the Sixties and was originally associated with consciousness-raising groups in the women’s movement — has been used to describe places in which members of historically persecuted groups can enjoy a reprieve from the hierarchies of the world at large and discuss their experiences without fear of censure. Some commentators viewed the…