 In such a sequence, each sentence \(\phi\) will either eventually stabilise on a classical truth value (true or false), or it will never stabilise. An example of a sentence that will never stabilise is the liar sentence: If the liar sentence is true in one of the languages \(L_{\alpha}\) it will be false in \(L_{\alpha +1}\), and vice versa. The revision theory thus gives an account of truth that correctly models the behaviour of the liar sentence as one that never stabilises on a truth value. In the revision theory it is argued that this gives a more correct account of truth and self-reference than Kripke’s theory in which the liar sentence is simply assigned the value undefined. Both the revision theory of truth and Kripke-style fixed-point theories are still being actively researched (Gupta and Standefer, 2017; Hsiung, 2017; Schindler, 2017). A full account of the revision theory can be found in the entry on  the revision theory of truth.  