 The early literature on presupposition almost exclusively revolved around definite descriptions, which are said to presuppose the existence of a unique referent. A problem arises when a definite description, like the King of France, fails to refer. Russell (1905) claimed that sentences like "The King of France is bald" are false because the logical form of definite descriptions contains a false existential claim. However, Strawson (1950) famously argued against Russell’s theory by proposing that when a definite description fails to refer, the result can be a sentence which lacks a truth value. Thus presuppositions are understood as definedness conditions, necessary requirements for an expression to have a meaning.