 Kripke’s ideas are based on an analysis of the problems involved in Tarski’s hierarchy approach. Kripke lists a number of arguments against having a language hierarchy in which each sentence lives at a fixed level, determined by its syntactic form. He proposes an alternative solution which still uses the idea of having levels, but where the levels are not becoming an explicit part of the syntax. Rather, the levels become stages in an iterative construction of a truth predicate. To explain Kripke’s construction, some additional technical machinery is required.