In general linguistics, a labile verb (or ergative / diffused / ambivalent verb) is a verb that undergoes causative alternation; that is, it can be used both transitively and intransitively, with the requirement that the direct object of its transitive use corresponds to the subject of its intransitive use, as in "I ring the bell" and "The bell rings." Labile verbs are a prominent feature of English, and also occur in many other languages. This behavior can be seen as evidence that the distribution of verb classes in that language does not depend on transitivity. In this respect, it is a phenomenon that is common to both Active languages and Ergative languages. In such languages it is often not possible to distinguish between transitive and intransitive verbs in terms of word formation or morphology. They have the same morphological form or suffix regardless of whether they are transitive or intransitive, and the transitivity or intransitivity of the verb is determined by the context.

When causatively alternating verbs are used transitively they are called causatives since, in the transitive use of the verb, the subject is causing the action denoted by the intransitive version. When causatively alternating verbs are used intransitively, they are referred to as anticausatives or inchoatives because the intransitive variant describes a situation in which the theme participant (in this case "the bell") undergoes a change of state, becoming, for example, "rung".

Terminology

The terminology in general linguistics is not stable yet. Labile verbs can also be called "S=O-ambitransitive" (following R. M. W. Dixon's usage), or "ergative", following Lyons's influential textbook from 1968. However, the term "ergative verb" has also been used for unaccusative verbs, and in most other contexts, it is used for ergative constructions.

In English

Most English verbs can be used intransitively, but ordinarily this does not change the role of the subject; consider, for example, "He ate the soup" (transitive) and "He ate" (intransitive), where the only difference is that the latter does not specify what was eaten. By contrast, with a labile verb the role of the subject changes; consider "it broke the window" (transitive) and "the window broke" (intransitive).

Labile verbs can be divided into several categories:

  • Verbs suggesting a change of state – break, burst, form, heal, melt, tear, transform
  • Verbs of cooking – bake, boil, cook, fry
  • Verbs of movement – move, shake, sweep, turn, walk
  • Verbs involving vehicles – drive, fly, reverse, run, sail

Some of these can be used intransitively in either sense: "I'm cooking the pasta" is similar to both "The pasta is cooking" (as an ergative verb) and "I'm cooking", although it is clearly more informative than either.

Unlike a passive verb, a nominalization, an infinitive, or a gerund, which allow the agent to be either excluded or included, the intransitive form of a labile verb normally requires the agent to be excluded:

  • "The window was broken" or "The window was broken by the burglar."
  • "[...] to break the window [...]" or "[...] for the burglar to break the window [...]"
  • "[...] the breaking of the window [...]" or "[...] the burglar's breaking of the window [...]"
  • "The window broke" but not "The window broke by the burglar."

The intransitive form of a labile verb can suggest that there is no agent. With some non-labile verbs, this can be achieved using the reflexive voice: He solved the problem becomes The problem was solved or The problem solved itself.

The first use of the passive voice can indicate the lack of an agent, but it can also be used when a specific agent is unknown. For example, the phrases "John broke the window, or maybe Jack did – at any rate, the window broke" and "John solved the problem, or maybe Jack did – at any rate, the problem was solved" both have quite naturally understandable meanings, though they are slightly idiomatic.

The second use of the reflexive voice indicates that the subject of the sentence is the causative agent; the phrase "John solved the problem, or maybe Jack did – at any rate, the problem solved itself" is literally self-contradictory, though idiomatic usage does not always follow this prescription. Accordingly, some grammarians would consider both "The window broke" and "The problem solved itself" to be examples of a distinct voice, the middle voice.

The labile verb enables not only the omission of the outside agent, but also the implication that the affected party is somehow causing the action. This can be done neutrally when the affected party can be considered an institution or corporate entity and the individual member responsible for the action is unimportant, for example "the shop closed for the day". It can also avoid assigning blame when journalists are sympathetic to a particular causative agent, as in "Eight factories have closed this year."

Another example

Example of the causative alternation with the English verb 'break':

In (7a), "x" is the variable ("stick"), and the CHANGE operator refers to the change-of-state ("break"). In the anticausative ("the stick broke") "the stick" undergoes the change "break", namely, the stick breaks. Moreover, the "y" variable refers to "Katherine" and the CAUSE operator refers to the cause of the change ("break"). In the causative, ("Katherine broke the stick"), it is "Katherine" who causes the action "break", and is therefore the cause operator.

The transitive/decausativation approach, assumes a lexical operation which performs precisely the opposite of the causativization approach discussed above.

In this approach, according to the following rule, the intransitive/anticausative form is derived from the transitive/causative form by deleting the cause predicate from the LCS. In example (8) below, the LCS is "Katherine broke the stick" and the cause predicate "Katherine" is deleted.

Syntactic

Under a syntactic intransitive base approach, the transitive form is derived from the intransitive form by insertion of a verbal layer projected by a head expressing causation and introducing the external agent argument. In addition, the layers are joined by head movement of the lowest verb head to positions higher in the syntactic structure. Change-of-state verbs are broken-down into the verbal layers of initiation phrase (initP), process phrase (procP) and result phrase (resP), which approximately correspond to the predicate cause, become, and state respectively.

Example (9a), the anticausative variant, is basic according to the intransitive base approach. The theme ("the stick") is initially merged into the specifier of resP and that it then moves to the specifier of procP. Around this time the causative alternations closely resemble an adult-like form; however, around the age of 2;6 to 12;0 children begin making common errors of overregularization, in which they erroneously overuse the causative. Children often acquire the syntactic pattern that goes along with verbal alternations; however, that does not mean that they acquire the lexical semantic restrictions that accompany these alternations.

In (29c), children are erroneously using fixed intransitive verbs (such as "stay") in environments where fixed transitive verbs (such as "keep") would be used.

In language acquisition, once children establish that a particular transitivity alternation is productive, they often extend the alternation to new verbs, It has been suggested that children learn this is through the no negative evidence problem; for example a child will learn that the verb 'throw' can never be used in a subject position: *"the ball threw". A reflexive pronoun is a pronoun that is preceded by the noun, adjective, adverb or pronoun to which it refers (its antecedent) within the same clause.

French

French is another language that has them, developed from lack of distinguished sense in Gallo-Roman Vulgar Latin:

  • "Il tourne la tête." ("He turns his head.")
  • "Sa tête tourne." ("His head turns.")

However, note that the use of the reflexive form of the verb to express the anticausative meaning is more common.

  • "Jouvre la porte." ("I open the door.")
  • "La porte s'ouvre." ("The door opens itself", i.e. "The door opens.")

Further, verbs analogous to English cook have even more possibilities, even allowing a causative construction to substitute for the transitive form of the verb:

  • "Je cuis les pâtes." ("I cook the pasta.")
  • "Je cuis." ("I cook", i.e. either "I cook [something]" or e.g. "It's so hot in here, I'm practically roasting.")
  • "Je fais cuire les pâtes." (lit., "I make cook the pasta", i.e. "I make the pasta cook", i.e. "I cook the pasta.")
  • "Les pâtes cuisent." ("The pasta cooks.")

French is a Romance language which incorporates the use of a reflexive pronoun with a verb's inchoative form.

Seen in (10) is the causative use of the verb "briser", conjugated in present tense.

Seen in (11) is the anticausative use of the verb.

Note the use of the reflexive pronoun "se" in (11), which is required for the sentence to be grammatically correct in French. Inchoative verbs in German are marked either by the reflexive pronoun "sich" (in third person), or not marked at all. Labile verbs are verbs that can be transitive or intransitive without morphological change, while paired verbs are verbs that require morphological changes in order to be read as transitive or intransitive.

Chinese

Mandarin Chinese is a language that lacks inflectional morphology that marks tense, case, agreement, or lexical category. The language also does not have derivational morphology to mark the transitivity of verbs.

Korean

Causative alternation in Korean is difficult to interpret. There have been many attempts to capture the restrictions on Korean causative alternation, but none of them capture the restrictions entirely.

Some verbs in Korean bear similarities to the paired verbs in Japanese. Morphological changes take place in order to show transitivity and intransitivity.

Shown in (25) is the causative use of the verb "열다" – yeolda, "to open", conjugated in the past-tense form yeoreotda.

Shown in (26) is the anticausative use of the verb, based on the anticausative form "열리다" - yeollida, conjugated in the past-tense form yeollyeotda.

In examples (25) and (26), it is seen that the infinitive (unconjugated) forms of the verb "yeolda" are the same, but causative and anticausative forms take on different conjugated forms in order to show causativity.

As an alternative analysis, the base verb "열다" – yeolda is inherently semantically causative/transitive, and "열리다" - yeollida is the anticausative/intransitive form, including the valency-changing infix "-리-" - -li-.

Korean also bears similarities to Chinese in its verbal compounding.

Shown in (27) and (28) is an example of a verb that requires compounding in order to be grammatical in the causative use.

Seen in (27) is the anticausative use of the verb "죽다" – jukda, conjugated in the past-tense form jugeotda.

Seen in (28) is the causative use of the verb, based on the causative form "죽이다" - jugida, conjugated in the past-tense honorific form jugyeotsumnda.