"Elegy plus comedy is the only way to express how we live in the world today, says a character in Sigrid Nunez's ninth novel. The Vulnerables offers a meditation on our contemporary era, as a solitary female narrator asks what it means to be alive at this complex moment in history and considers how our present reality affects the way a person looks back on her past. Humor, to be sure, is a priceless refuge. Equally vital is connection with others,...