Nouns and Interrogative Complements

Question

In English, there are many different verbs which can combine with clausal complements. These verbs can be further sub-categorised as to whether they embed a propositional that-clause, or an embedded question. Some verbs, such as believe, may only embed a proposition (i). Other verbs, like wonder, may only embed a question (ii), and still other verbs, like know, may embed either a proposition or a question (iii).

• i. a. John believed [that Mary came]
  b. *John believed [who came]
• ii. a. *John wondered [that Mary came]
  b. John wondered [who came]
• iii. a. John knows [that Mary came]
  b. John knows [who came]

My question concerns the properties of nouns that can combine with clausal complements, and how they relate to the paradigm above. Note that there are many nouns, such as belief that can combine directly with a propositional clausal complement. They do not require a prepositional element (iv), unlike Noun Phrase complements to Nouns (v).

• iv. a. The belief [that evolution is false] is thankfully extremely rare.
  b. *The belief of [that evolution is false] is thankfully extremely rare.
• v. a. *The photograph John is being developed.
  b. The photograph of John is being developed.

Surprisingly, based on my tentative investigations, nouns which combine with questions are rather uncommon, and those that can combine with questions require a prepositional element (vi). In this respect question complements to nouns seem to behave more like DPs than that-clauses.

• vi. a. *The knowledge [who came] is extremely valuable.
  b. The knowledge of [who came] is extremely valuable.

My question has an empirical aspect and a theoretical aspect: (1) The empirical question is to what extent this set of facts is unique to English. Are there other languages where interrogative clauses can freely combine with nouns? What happens in languages with case-marking for example? (2) The theoretical question is why question complements to nouns would behave more like Noun Phrase complements than that-clause complements.

Answer 1

Concerning the first question, German behaves similar to English regarding the content clauses that nouns can and cannot take, e.g.

 1a. die Tatsache, dass er das gemacht hat
     'the fact that he did that'

 1b. *die Tatsache, wann er das gemacht hat
     'the fact when he did that'

 2a. *die Frage, dass er das gemacht hat
     'the question that he did that'

 2b.  die Frage, warum er das gemacht hat
      'the question why he did that'

German has morphological case, but I am not aware that this fact has any influence at all on the distribution of content clauses (that's what I've encountered these clauses called, i.e. content clauses). Whether or not a given noun can take a declarative or interrogative content clause is an idiosyncratic trait of the noun; it is a lexical matter, i.e. part of the valency of the noun. Certainly semantic considerations play a role in determining valency traits, but my guess is that semantics will get you only so far.

The second question receives a clear answer that is purely syntactic in nature (as opposed to lexico-semantic). that-clauses have a distribution that is more limited than embedded wh-clauses. In particular, wh-clauses can easily appear as the complement of a preposition, whereas that-clauses really cannot, e.g.

 3a  *We looked at that he did that.
 3b.  We looked at why he did that.

 4a. *They talked about that he did that.
 4b.  They talked about why he did that.

 5a. *the discussion of that he did that
 5b.  the discussion of why he did that

 6a. *We were struggling with that he did that.
 6b.  We were struggling with why he did that.

These data motivate the stance that prepositions can freely take wh-clauses as complements, but not that-clauses. Of course the pertinent question is why this should be the case. I believe there is a solid syntactic explanation.

This explanation resides with the analysis of that-clauses and wh-clauses (matrix vs. embedded). If one assumes that the head/root of a that-clause is the subordinator that and the head/root of an embedded wh-clause is the wh-element, then the explanation comes into view. The subordinator that does not have the status of of a nominal, whereas wh-elements do (because of their wh-feature). In other words, prepositions are subcategorizing for a nominal dependent; that-subordinators do not have nominal status, whereas wh-subordinators and wh-elements do have this status.

This explanation relies crucially on the stance that the wh-element is the head/root of the embedded wh-clause. So for instance, in the following embedded wh-clause, the wh-element is the head/root of that clause:

7. the explanation about why he did that

By assuming that why is the head/root of the clause why he did that, we can produce a coherent syntactic explanation of the acceptability judgments in 1-7. The wh-feature on why renders why the equivalent of a nominal category, which means that it can be the immediate dependent of a preposition. Since the subordinator that lacks the wh-feature, it cannot be the immediate dependent of a preposition.

I address this issue (i.e. the analysis of matrix and embedded wh-clauses) directly in two of my/our publications. I would be happy to provide copies to anyone who is interested (my email is [email protected]).

And one further point: the overarching issue is touched on briefly in an (in my view convincing) argument against syntactic movement. Observe the following acceptability contrast -- the examples are taken from Wikipedia:

 8a. *We talked about that he was sick for days.  
 8b.  That he was sick, we talked about for days. 

This acceptability contrast consitutes what is known as a movement paradox; it is originally due to Joan Bresnan, I think. If topicalization really involved syntactic movement, then both of these sentences should be acceptable. The fact that 8a is bad demonstrates that the topicalized clause in 8b cannot have originated in its "base" position shown in 8a.