 Kripke’s iterative construction of a truth predicate presented above may be viewed as an instance of a more general fixed point approach towards building formal theories of truth. Fixed point approaches have become central to contemporary formal theories of truth. The main idea is to have a truth revision operator and then look for fixed points of this operator. At heart of such fixed point approaches is some suitable fixed point theorem guaranteeing the existence of fixed points for certain kinds of operators. There are several different fixed point theorems available. Consider now one of the simpler ones.