Chomsky’s three levels of adequacy

Smith and Wilson (1979: 241–2) provide a good example of Chomsky’s three levels of adequacy. In the case of what is known as WH-movement, a noun following a WH- word can be moved to the front of a sentence:

1 Mary met some tourist on the street.

1b Which tourist did Mary meet on the street?

But this movement is not possible for a noun in a co-ordinated NP of the form ‘X and Y’:

2 Mary met a policeman and some tourist on the street.

2b *Which tourist did Mary meet a policeman and on the street?

An observationally adequate grammar would merely state that WH-movement does not allow extraction of a noun or noun-phrase from a co-ordinated structure, but in doing so it might miss a more important generalization, namely that the same constraint also applies elsewhere. Movement from a conjoined NP is similarly ruled out in topicalization, for example:

3 I want to invite that boy to my party

3b That boy, I want to invite to my party.

4 I want to invite this girl and that boy to my party

4b This girl and that boy, I want to invite to my party

4c *That boy, I want to invite this girl and to my party.

A descriptively adequate grammar of English would therefore state that no rule of English – and, equally importantly, no possible rule of English – allows movement out of a co-ordinated NP. But an explanatorily adequate grammar of English would not specify the rule at all, because it seems to be a feature of universal grammar. Movement from co-ordinated NPs appears to be ruled out in other languages, with no known counter-examples:

French:

J’aime beaucoup ton frère et ta sœur ‘I like your brother and your sister’

*Ta sœur, j’aime beaucoup ton frère et *‘Your sister, I like your sister and’

Russian:

Ja vidjel Pavla i Sonju ‘I saw Pavel and Sonya’

*Sonju ja vidjel Pavla i *‘Sonya I saw Pavel and’

Nupe (Nigeria):

egi-zì gí yikã tò n`â? ‘(The) children ate fish and meat’

*n¯ak`â kíci egi-zì gí yikã tò o? *‘meat which children eat fish and’ (*‘Which meat did the children eat fish and’?)