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.