“Just because an artist is not thinking directly about politics while making a work does not mean they are outside the political context,” said Xuxa Rodríguez, curator of “Turn the Volume Up!,” the newest exhibition at Duke University’s Nasher Museum of Art. The timely—or timeless—exhibition surveys art’s place in both the great and mundane moments of social justice. While it would not be wholly inaccurate to call it a show of protest art, that label doesn’t capture the full scope of Rodríguez’s imagination. Using the ideological drama of the United States’ 250th anniversary as fuel, she has reanimated a century-spanning archive of posters, paintings, sculptures, and photographs into urgent imperatives: Vote. Petition. Meet your neighbors.