Why did Russell develop a theory of definite descriptions?

Bertrand Russell developed his theory of definite descriptions primarily to resolve philosophical puzzles regarding meaningful statements that contain descriptions that do not refer to any existing object, such as "The present king of France is bald."12

Prior to Russell, philosophers like Alexius Meinong argued that for such sentences to be meaningful, there must be some "mysterious" realm of non-existent entities for these descriptions to refer to. Russell rejected this, arguing that such thinkers were misled by the surface grammatical form of language. He proposed that definite descriptions are not singular terms that refer to objects, but are instead complex, existentially quantified expressions.123

By analyzing "The present king of France is bald" as a conjunction of three claims—that there is a king of France, that there is at most one, and that he is bald—Russell demonstrated that the sentence is false rather than nonsensical, without requiring a referent. This analysis allowed philosophers to avoid positing unnecessary "logical fictions" and helped establish the program of analytic philosophy by using modern logic to uncover the true logical form of language.12