Ever since he first burned into the American consciousness with "The Revolution Will Not Be Televised" in 1971, Gil Scott-Heron has been an indispensable voice of conscience and liberation. His worldview is unabashedly Afro-centric, but he doesn't waste time with whitey-bashing or negativity: the music, accessibly melodic, has a loose, life-affirming groove and rhythmic influences that span the globe (From South Africa to South Carolina is the title of one of his LPs). Thematically, Scott-Heron is an unreconstructed maverick: "Gun" challenges gun control from the perspective of the ghetto dweller ("When they give up theirs I'll give up mine"); he criticizes black macho in "Ain't No Such Thing as Superman," but then dedicates "You May Not Be in a Class by Yourself, but It Don't Take Long to Call the Roll" to "women who think more of themselves than we do." Alongside his tender paeans to African American culture ("Lady Day and John Coltrane") and his famous presidential rogues' gallery ("Skippy" Carter, "Oatmeal Man" Ford, "Hollyweird" Reagan--what he'll do with Bush and Quayle I don't know, but the anticipation is delicious!), Scott-Heron's audacity, joy, and outrage continue to delight and instruct. Saturday, Biddy Mulligan's, 7644 N. Sheridan; 761-6532.