Inversion

In linguistics, inversion is any of several grammatical constructions where two expressions switch their canonical order of appearance, that is, they invert. The most frequent type of inversion in English is subject–auxiliary inversion, where an auxiliary verb changes places with its subject; this often occurs in questions, such as Are you coming?, where the subject you is switched with the auxiliary are. In many other languages – especially those with freer word order than English – inversion can take place with a variety of verbs (not just auxiliaries) and with other syntactic categories as well.

When a layered constituency-based analysis of sentence structure is used, inversion often results in the discontinuity of a constituent, although this would not be the case with a flatter dependency-based analysis. In this regard inversion has consequences similar to those of shifting.

Inversion in English

In broad terms, one can distinguish between two major types of inversion in English that involve verbs: subject–auxiliary inversion and subject–verb inversion.^[1] The difference between these two types resides with the nature of the verb involved, i.e. whether it is an auxiliary verb or a full verb.

Subject–auxiliary inversion

The most frequently occurring type of inversion in English is subject–auxiliary inversion. The subject and auxiliary verb invert, i.e. they switch positions, e.g.

a. Fred will stay.

b. Will Fred stay? - Subject–auxiliary inversion with yes/no question

a. Larry has done it.

b. What has Larry done? - Subject–auxiliary inversion with constituent question

a. Fred has helped at no point.

b. At no point has Fred helped. - Subject–auxiliary inversion with fronted expression containing negation (negative inversion)

a. If we were to surrender, ...

b. Were we to surrender, ... - Subject–auxiliary inversion in condition clause – see English subjunctive: Inversion in condition clauses

The default order in English is subject–verb (SV), but a number of meaning-related differences (such as those illustrated above) motivate the subject and auxiliary verb to invert so that the finite verb precedes the subject; one ends up with auxiliary–subject (Aux-S) order. This type of inversion fails if the finite verb is not an auxiliary:

a. Fred stayed.

b. *Stayed Fred? - Inversion impossible here because the verb is NOT an auxiliary verb

(The star * is the symbol used in linguistics to indicate that the example is grammatically unacceptable.)

Subject–verb inversion

The verb in cases of subject–verb inversion in English is not required to be an auxiliary verb; it is, rather, a full verb or a form of the copula be. If the sentence has an auxiliary verb, the subject is placed after the auxiliary and the main verb. For example:

a. A unicorn will come into the room.

b. Into the room will come a unicorn.

Since this type of inversion generally places the focus on the subject, the subject is likely to be a full noun or noun phrase rather than a pronoun. Third-person personal pronounsare especially unlikely to be found as the subject in this construction. For example:

a. Down the stairs came the dog. - Noun subject

b. ? Down the stairs came it. - Third-person personal pronoun as subject; unlikely unless it has special significance and is stressed

c. Down the stairs came I. - First-person personal pronoun as subject; more likely, though still I would require stress

There are a number of types of subject-verb inversion in English: locative inversion, directive inversion, copular inversion, and quotative inversion. See the article on subject-verb inversion.