Donkey sentence

In semantics, donkey sentences are sentences that contain a pronoun with clear meaning (it is semantically bound) but whose syntactic role in the sentence poses challenges to linguists. Such sentences defy straightforward attempts to generate their formal language equivalents. The difficulty is with understanding how English speakers parse such sentences.

Barker and Shan define a donkey pronoun as "a pronoun that lies outside the restrictor of a quantifier or the if-clause of a conditional, yet covaries with some quantificational element inside it, usually an indefinite." The pronoun in question is sometimes termed a donkey pronoun or donkey anaphora.

The following sentences are examples of donkey sentences.

• "Omne homo habens asinum videt illum." ("Every man who owns a donkey sees it") — Walter Burley (1328), De puritate artis logicae tractatus longior
• "Every farmer who owns a donkey beats it."
• "Every police officer who arrested a murderer insulted him."