ORADORES, ORADORES, ORADORES: William Cordova’s sculpture is the Kaaba at Mecca, the monolith from 2001, and a thrift-store storage room rolled into one.

In a world that seems ever more synthetic and controlling, street art poses as a guerrilla force pushing back. Its rascally, outlaw, bad-boy cool feels free, real. Our postmodern (or maybe early post-postmodern) art world suffers from its own artificiality complex. So it mines urban style for authenticity, for energy, for street cred. Which brings us to “Street Level,” the fun, hip new exhibit organized by Duke University’s Nasher Museum and now up at the Institute of Contemporary Art, with work by Mark Bradford, William Cordova, and Robin Rhode.

The South Africa–born, Berlin-based Rhode seems to enter into the chalk-and-oil stick drawings that he graffitis onto walls and streets like a hip-hop Harold and the Purple Crayon. In his lyrical 2005 video Untitled, Harvest, we watch a series of still shots of Rhode planting (chalk) seeds and watering them. They sprout wavy chalk lines with dots on top that he mows down with a scythe. They sprout again forming a bed frame, and he lies down under a real sheet — maybe just a sleeping man or maybe a corpse under a shroud. In his 2004 video He Got Game, Rhode sketches a basketball hoop with chalk on pavement and then seems to leap, somersault, and dunk a real basketball. The magic is in his held poses, which feel like frozen frames of action, and in the framing. The camera looks down at the ground, but we feel that we’re looking across at a wall, so though Rhode is lying on the ground, he seems to be flying through the air.

Los Angeles artist Mark Bradford collects posters from city walls and fences and pastes them into giant collages. Europeans like Mimmo Rotella made stuff like this in the ’60s, but Rotella tended to retain the posters’ imagery, whereas Bradford often creates abstract patterns that recall maps of cities. Temporary (2005) is a billboard-sized expanse of white paper dotted with asymmetrical urban-like grids of pink, black, and gray paper or tape with red yarn lines circulating through. Bradford often layers paper over yarn and then tears, sands, and scrapes it down, making his surfaces seductively ragged and worn, like the patchwork layers of posters you see pasted around cities. His art has the grandeur and gritty nostalgia of shuttered mills and abandoned buildings — our modern ruins.

UNTITLED DREAM HOUSES: Robin Rhode seems to enter into the chalk-and-oil stick drawings that he graffitis onto walls and streets.

All these people — activists and radicals — are either old or dead. “Oradores” is Spanish for “orators,” and there’s the double meaning in English of “speakers” as both orators and stereo equipment (stereo speaker being “altavoz” in Spanish). The dead speakers are a wall of sound that has been silenced. But Cordova also seems to be punning on “orar,” Spanish for “to pray” — turning the sculpture into a shrine while suggesting what options we’re left with.