X-bar theory

The X -bar theory (also: X - bar syntax) in 1977 formulated by Jackendoff based on Noam Chomsky. It is a part of a linguistic theory and states that the syntactic structures of all natural languages ​​common design principles are.

According to the theory there are all natural languages ​​from phrases that are hierarchical. These can be abstract in a tree structure, the so-called X - bar schema shown. For instance, contains a verb phrase such as " handed over to the Minister the petition " a so-called phrase header - here the word " handed over ". This calls for further parts of a sentence, called arguments. In the previous example calls the phrase header (X) " handed over " the arguments directly ( P ") (here:" the Petition " ) and indirect (here:" the Minister " ) object (P '). A phrase that has all the required arguments is, a maximum of ( X "). Phrase header and maximum phrase share a number of characteristics which are also called head features. In the example, the head determines " handed over " inter alia, the person and Numerusmerkmale the verb phrase. It is said, therefore, that the verb phrase is the maximum projection of the verbal head.

X - bar schema

The core of the X-Bar Theory, the so-called X - bar scheme may be formulated in a recursive version of the following:

X stands for a set of head features. Rule 1 states that a phrase header X together with a further maximum phrase P " that is demanded of X, a phrase X '. X 'and X have the same head properties. P "is the supplement or complement.

Rule 2 allows recursively more phrases P ". These are referred to as data.

Rule 3 finally allows the formation of a maximum phrase X "of the intermediate plane X ' and another argument P", which can, however, also be missing ( indicated by parentheses ). P "is the specifier or specifiers. The set notation in the rules 1 ) to 3) to clarify that the sequence of X and X ' and P " is in principle arbitrary, so the phrase header can be used both in front of his argument as a stand afterwards.

Instances of the X - bar schema

Instantiates to the above X - bar schema with concrete syntactic categories - for example, verb (V) and noun phrase (N ' ) -, we obtain the following phrase structure rules:

V stands for example for the feature set { category = verb, person = 1, numerus = plural, tense = Praet mode = indicative }.

Since the X - bar schema in principle on generated - ie allow more arguments than are actually required - it must be limited by other mechanisms again.


Since the X -bar theory starts from a basic syntactic understanding that every human being is innate, it is controversial in linguistics. Evidence for this assumption could not yet be delivered. This general conflict took place in the so-called Linguistic Wars its peak. In addition, the number and allocation of categories is controversial.