Wh-movement
In linguistics, wh-movement is the formation of syntactic dependencies involving interrogative words. An example in English is the dependency formed between what and the object position of doing in "What are you doing?". Interrogative forms are sometimes known within English linguistics as wh-words, such as what, when, where, who, and why, but also include other interrogative words, such as how. This dependency has been used as a diagnostic tool in syntactic studies as it can be observed to interact with other grammatical constraints.
In languages with wh-movement, sentences or clauses with a wh-word show a non-canonical word order that places the wh-word at or near the front of the sentence or clause instead of the canonical position later in the sentence. Leaving the wh-word in its canonical position is called wh-in-situ and in English occurs in echo questions and polar questions in informal speech.
Wh-movement is one of the most studied forms of linguistic discontinuity. It is observed in many languages and plays a key role in the theories of long-distance dependencies.
The term wh-movement stemmed from early generative grammar in the 1960s and 1970s and was a reference to the theory of transformational grammar, in which the interrogative expression always appears in its canonical position in the deep structure of a sentence but can move leftward from that position to the front of the sentence/clause in the surface structure. Although other theories of syntax do not use the mechanism of movement in the transformative sense, the term wh-movement is widely used to denote the phenomenon, even in theories that do not model long-distance dependencies as a movement.
Basic examples
The following examples of sentence pairs illustrate wh-movement in main clauses in English: each example has the canonical word order of a declarative sentence in English, while each sentence has undergone wh-movement, whereby the wh-word has been fronted in order to form a direct question.Wh-fronting of whom, which corresponds to the direct object Tesnière.
Wh-fronting of what, which corresponds to the prepositional object syntax.
Wh-fronting of when, which corresponds to the temporal adjunct tomorrow.
Wh-fronting of what, which corresponds to the predicative adjective happy.
Wh-fronting of where, which corresponds to the prepositional phrase to school.
Wh-fronting of how, which corresponds to the adverb phrase well.
These examples illustrate that wh-movement occurs when a constituent is questioned that appears to the right of the finite verb in the corresponding declarative sentence. The main clause remains in V2 word order, with the interrogative fronted to first position while the finite verb stays in second position. Do-support is often needed to enable wh-fronting in such cases, which are reliant on subject–auxiliary inversion.
Subject "fronting"
When the subject is questioned, it is unclear whether wh-fronting has occurred because the default position of the subject is clause-initial. In the example sentence pair below, the subject Fred already appears at the front of the sentence where the interrogative is placed.Some theories of syntax maintain that this constitutes a wh-movement, and analyze such cases as if the interrogative subject has moved up the syntactic hierarchy; however, other theories observe that the surface string of words remains the same, and therefore, no movement has occurred.
Distance of movement
In many cases, wh-fronting can occur regardless of how far away its canonical location is, as seen in the following set of examples:The interrogative whom is the direct object of the verb like in each of these examples. The dependency relation between the canonical, empty position and the wh-expression appears to be unbounded, in the sense that there is no upper bound on how deeply embedded within the given sentence the empty position may appear.
Wh-expressions without wh-movement
Wh-movement typically occurs when forming questions in English. There are certain forms of questions in which wh-movement does not occur :- Echo questions: Confirming what you thought you heard.
- *You bought what?
- Quiz questions or specific questions: Asking for detailed specific information.
- *George Orwell was born in which country?
- Multiple interrogatives in a single sentence.
- *Who bought what?
- Expected questions: Occur when new information is expected.
In-situ questions are different from wh-fronted questions in that they result from no movement at all, which tends to be morphologically or pragmatically conditioned.
In subordinate clauses
The basic examples above demonstrate wh-movement in main clauses in order to form a direct question. Wh-movement can also occur in subordinate clauses, although its behavior in subordinate clauses differs in word order.In indirect questions
In English, wh-movement occurs in subordinate clauses to form an indirect question. While wh-fronting occurs in both direct and indirect questions, there is a key word order difference, as illustrated with the following examples:In indirect questions, while the interrogative is still fronted to the first position of the clause, the subject is instead placed in second position, and the verb appears in third position, forming a V3 word order.
In relative clauses
Although many examples of wh-movement form questions, wh-movement also occurs in relative clauses. Many relative pronouns in English have the same form as the corresponding interrogative words. Relative clauses are subordinate clauses, so the same V3 word order occurs.The relative pronouns have fronted in the subordinate clauses of the b. examples. The characteristic V3 word order is obligatory, just as in other subordinate clauses.
Pied-piping
Many instances of wh-fronting involve pied-piping, where the word that is moved pulls an entire encompassing phrase to the front of the clause with it. Pied-piping was first identified by John R. Ross in his 1967 dissertation.Obligatory pied-piping
In some cases of wh-fronting, pied-piping is obligatory, and the entire encompassing phrase must be fronted for the sentence to be grammatically correct. In the following examples, the moved phrase is underlined:These examples illustrate that pied-piping is often necessary when the wh-word is inside a noun phrase or adjective phrase. Pied-piping is motivated in part by the barriers and islands to extraction. When the wh-word appears underneath a blocking category or in an island, the entire encompassing phrase must be fronted.
Optional pied-piping
There are other cases where pied-piping is optional. In English, this occurs most notably when the fronted word is the object of a prepositional phrase. A formal register will pied-pipe the preposition, whereas more colloquial English prefers to leave the preposition in situ:The c. examples are cases of preposition stranding, which is possible in colloquial English but not allowed in many languages that are related to English. For instance, preposition stranding is largely absent from many of the other Germanic languages, and it may be completely absent from the Romance languages. Prescriptive grammars often claim that preposition stranding should be avoided in English as well, although it may feel artificial or stilted to a native speaker to move the preposition.
Extraction islands
A syntactic island is a construction from which extracting an element leads to an ungrammatical or marginal sentence. For example:These types of phrases, also referred to as extraction islands or simply islands, do not allow wh-movement to occur. John R. Ross proposed and described four types of islands: Complex-Noun Phrase Constraints, Coordinate Structure Constraint, Left Branch Condition, and Sentential Subject Constraint. Configurations showing clear island restrictions have also been called wh-islands, complex noun phrases, and adjunct islands.
Adjunct islands
An adjunct island is a type of island formed from an adjunct clause. Wh-movement is not possible from an adjunct clause. Adjunct clauses include clauses introduced by because, if, and when, as well as relative clauses. Instead, a question would be formed by keeping the interrogative in situ. For example:Wh-islands
A wh-island is created by an embedded sentence that is introduced by a wh-word, creating a dependent clause. Wh-islands are weaker than adjunct islands, and violating them results in a sentence that at minimum sounds ungrammatical to a native speaker.The b. sentences are strongly marginal or unacceptable because they attempt to extract an expression out of a wh-island. This occurs because both wh-words are part of a DP. It would not be possible to move the bottom wh-word to the top of the structure, as they would both interfere. In order to get a grammatical result, a proper wh-movement must occur. However, because the wh-word is taking up the Spec-C position, it is not possible to move the competing wh-word higher by skipping the higher DP as wh-movement is a cyclic process.