 Tarski’s hierarchy approach to the semantic paradoxes dominated the field until 1975, when Kripke published his famous and highly influential paper, “Outline of a Theory of Truth”. This paper has greatly shaped most later approaches to theories of truth and the semantic paradoxes. It should be noted, however, that ideas quite similar to Kripke’s were developed simultaneously and independently by Martin and Woodruff (1975), and that a parallel approach in a set-theoretic setting was developed independently by Gilmore (1974).