Manifestations
Recursion tends to be portrayed either as being a characteristic of clause subordination, or more generally as a ubiquitous phenomenon of language, in that the latter has been portrayed as a recursively generated system producing discrete infinity. Neither of these views is entirely appropriate. Clause subordination is not really the domain where recursion manifests itself most frequently in normal language use, nor is recursion found everywhere in language, nor is embedding recursion the only type of rule that is responsible for discrete infinity, nor is discrete infinity something that is in any way characteristic of the way languages are used. Perhaps most commonly, recursion occurs in noun phrase discourse.1 Outside phrase structure, recursion is less easy to find in language structure; as Pinker and Jackendoff (2005: 216) observe, a case marker may not normally contain another instance of a case marker; an article may not contain an article; a pronoun may not contain a pronoun, and so on for auxiliaries, tense features, etc., and recursion is also absent at the phonological level.2
English allows recursive compounds (3a), adjectives (3b), attributive possession (3c), adverbial phrases (3d), and clause embedding (3e), but not really recursive verbs, affixes, or other constituents. Note that the following examples have contrasting branching directions, being left-branching in (a), (b), and (c), but right-branching in (d) and (e).
(3) English
a. [[[frog]man]team]leader
b. [[[new] big] red] cars
c. [[[[Peter’s] mother’s] brother’s] wife’s] father
d. the book [on the table [in the room [behind my office]]]
e. Judy says [that John claims [that Mary believes [that I want to marry her]]].
However, recursion is not restricted to the internal structure of a sentence— neither in English nor in many other languages; rather, it can also involve direct speech sentences, cf. (4).
(4) English
Judy said: [‘‘John told me yesterday: [‘‘I want to marry you.’’]’’].
It would be futile to define all the components of grammar that exhibit recursion since this is a theory-related issue. Accordingly, depending on how one defines (embedding) grammatical categories, one will come up with different views on the exact range of recursive structures that exist. For example, if one were to follow those for whom auxiliaries and main verbs are both verb phrases (VPs), one could argue that there is recursion in verb phrases—that is, something like [VP [VP]], and a theory postulating only one type of grammatical category would be able to produce a grammar with a maximum of recursive structures.
1 This statement is based on impressionistic observations; we are not aware of any quantitative data on the magnitude of recursive structures in language use.
2 Phonology is hierarchical but not recursive (Fitch, Hauser, and Chomsky in press: 17).
