Donkey sentence

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Donkey sentences are sentences that contain a pronoun whose reference is clear to the reader (it is bound semantically) but whose syntactical role in the sentence poses challenges to grammarians.[1][2] 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[3][4]
  • Every farmer who owns a donkey beats it.[5]
  • Every police officer who arrested a murderer insulted him.

Such sentences defy straightforward attempts to generate their formal language equivalents, the difficulty is with understanding how English speakers parse such sentences.[6]


Walter Burley, a medieval scholastic philosopher, introduced donkey sentences in the context of the theory of suppositio, the medieval equivalent of reference theory.

Peter Geach reintroduced donkey sentences as a counterexample to Richard Montague's proposal for a generalized formal representation of quantification in natural language (see Geach 1962). His example was reused by David Lewis (1975), Gareth Evans (1977) and many others, and is still quoted in recent publications.


Features of the sentence, "Every farmer who owns a donkey beats it," require careful consideration for adequate description (though reading "each" in place of "every" does simplify the formal analysis), the donkey pronoun in this case is the word it. The indefinite article 'a' is normally understood as an existential quantifier, but the most natural reading of the donkey sentence requires it to be understood as a nested universal quantifier.

There is nothing wrong with donkey sentences: they are grammatically correct, they are well-formed, their syntax is regular, they are also logically meaningful, they have well-defined truth conditions, and their semantics are unambiguous. However, it is difficult to explain how donkey sentences produce their semantic results, and how those results generalize consistently with all other language use. If such an analysis were successful, it might allow a computer program to accurately translate natural language forms into logical form,[7] the question is, how are natural language users, apparently effortlessly, agreeing on the meaning of sentences like these?

There may be several equivalent ways of describing this process; in fact, Hans Kamp (1981) and Irene Heim (1982) independently proposed very similar accounts in different terminology, which they called discourse representation theory (DRT) and file change semantics (FCS) respectively.

In 2007, Adrian Brasoveanu published studies of donkey pronoun analogs in Hindi, and analysis of complex and modal versions of donkey pronouns in English.

Discourse representation theory[edit]

Donkey sentences became a major force in advancing semantic research in the 1980s, with the introduction of discourse representation theory (DRT). During that time, an effort was made to settle the inconsistencies which arose from the attempts to translate donkey sentences into first-order logic.

Donkey sentences present the following problem, when represented in first-order logic: The systematic translation of every existential expression in the sentence into existential quantifiers produces an incorrect representation of the sentence, since it leaves a free occurrence of the variable y in BEAT(x.y):

Trying to extend the scope of existential quantifier also does not solve the problem:

In this case, the logical translation fails to give correct truth conditions to donkey sentences: Imagine a farmer not beating his donkey, the formula will be true in that situation, because for each farmer we need to find at least one object that either is not a donkey, or not owned by this farmer, or is beaten by the farmer. Hence, if this object denotes a pig he also owns, anything unrelated, or even the farmer himself, the sentence will be true in that situation.

A correct translation into first-order logic for the donkey sentence seems to be:

Unfortunately, this translation leads to a serious problem of inconsistency. One possible interpretation, for example, might be that every farmer that owns any donkeys beats every donkey. Clearly this is rarely the intentional meaning. Indefinites must sometimes be interpreted as existential quantifiers, and other times as universal quantifiers, without any apparent regularity.

The solution that DRT provides for the donkey sentence problem can be roughly outlined as follows: The common semantic function of non-anaphoric noun phrases is the introduction of a new discourse referent, which is in turn available for the binding of anaphoric expressions. No quantifiers are introduced into the representation, thus overcoming the scope problem that the logical translations had.

See also[edit]


  1. ^ Emar Maier describes donkey pronouns as "bound but not c-commanded" in a Linguist List review of Paul D. Elbourne's Situations and Individuals (MIT Press, 2006).
  2. ^ Barker and Shan define a donkey pronoun as "a pronoun that lies outside the restrictor of a quantifier or the antecedent of a conditional, yet covaries with some quantificational element inside it, usually an indefinite." Chris Barker and Chung-chieh Shan, 'Donkey Anaphora is Simply Binding' Archived May 15, 2008, at the Wayback Machine., colloquium presentation, Frankfurt, 2007.
  3. ^ Gualterus Burlaeus (1988). De puritate artis logicae tractatus longior. Meiner Verlag. 
  4. ^ Keith Allan (2010). Concise Encyclopedia of Semantics. Elsevier. 
  5. ^ Peter Geach (1962). Reference and Generality. 
  6. ^ David Lewis describes this as his motivation for considering the issue in the introduction to Papers in Philosophical Logic, a collection of reprints of his articles. "There was no satisfactory way to assign relative scopes to quantifier phrases." (CUP, 1998: 2.)
  7. ^ Alistair Knott, 'An Algorithmic Framework for Specifying the Semantics of Discourse Relations', Computational Intelligence 16 (2000).


  • Kamp, H. and Reyle, U. 1993. From Discourse to Logic. Kluwer, Dordrecht.
  • Kadmon, N. 2001. Formal Pragmatics: Semantics, Pragmatics, Presupposition, and Focus. Oxford: Blackwell Publishers.

Further reading[edit]

External links[edit]