Relative Clause - Accessibility Hierarchy

Accessibility Hierarchy

The antecedent of the relative clause (that is, the noun that is modified by it) can in theory be the subject of the main clause, or its object, or any other verb argument. In many languages, however, especially rigidly left-branching, dependent-marking languages with prenominal relative clauses, there are major restrictions on the role the antecedent may have in the relative clause.

Edward L. Keenan and Bernard Comrie noted that these roles can be ranked cross-linguistically in the following order from most accessible to least accessible:

Subject > Direct Object > Indirect Object > Oblique > Genitive > Object of comparative

Ergative–absolutive languages have a similar hierarchy:

Absolutive > Ergative > Indirect Object > etc. (same as above)

This order is referred to as the accessibility hierarchy. If a language can relativize positions lower in the accessibility hierarchy, it can always relativize positions higher up, but not vice versa. For example, Malagasy can relativize only subject and Chukchi only absolutive arguments, whilst Basque can relativize absolutives, ergatives and indirect objects, but not obliques or genitives or objects of comparatives. Similar hierarchies have been proposed in other circumstances, e.g. for pronominal reflexes.

English can relativize all positions in the hierarchy. Here are some examples of the NP and relative clause usage from English:

Some other examples:

Languages which cannot relativize directly on noun phrases low in the accessibility hierarchy can sometimes use alternative voices to "raise" the relevant noun phrase so that it can be relativized. The most common example is the use of applicative voices to relativize obliques, but in such languages as Chukchi antipassives are used to raise ergative arguments to absolutive.

For example, a language that can relativize only subjects could say this:

• The girl came to visit.

But not:

• *The girl came to visit.
• *The girl came to visit.
• *The girl came to visit.
• *The girl came to visit.
• *The girl came to visit. (equivalent to previous)
• *The girl came to visit.

These languages might form an equivalent sentence by passivization:

• The girl came to visit.
• The girl came to visit.
• The girl came to visit.
• The girl came to visit.
• The girl came to visit.

Note that these passivized sentences get progressively more ungrammatical in English as they move down the accessibility hierarchy; the last two, in particular, are so ungrammatical as to be almost unparsable by English speakers. However, those languages with severe restrictions on which roles can be relativized are precisely those that can passivize almost any position, and hence the last two sentences would be normal in these languages.

A further example is languages that can relativize only subjects and direct objects. Hence the following would be possible:

• The girl came to visit.

However, the other ungrammatical examples above would still be ungrammatical. These languages often allow an oblique object to be moved to the direct object slot by the use of the so-called applicative voice, similar to how the passive voice moves an oblique object to the subject position. The above examples expressed in an applicative voice might be similar to the following (in not necessarily grammatical English):

• The girl came to visit.
• The girl came to visit.
• The girl came to visit.
• The girl came to visit.

Modern grammars may use the accessibility hierarchy to order productions — e.g. in Head-Driven Phrase Structure Grammar the hierarchy corresponds to the order of elements on the subcat list, and interacts with other principles in explanations of binding facts. The hierarchy also figures in Lexical Functional Grammar where it is known as Syntactic Rank or the Relational Hierarchy.