We present BFL, a hybrid logic for representing uncertain knowledge. BFL attaches a quantified notion of belief based on Dempster-Shafer’s theory of belief functions to classical first-order logic. The language of BFL is composed of objects of the form F:[a,b], where F is a first-order sentence, and Q and b are numbers in the [O,l] interval (with c&b). Intuitively, a measures the strength of ou...