Quote Originally Posted by Hephaestus View Post
"What does John know Mary bought?"

Consider a spy movie--or Christmas. John knows Mary bought things, but someone wants to know what John knows Mary bought. Maybe they're hoping he doesn't know about something she bought. Questioning what someone knows about another person's actions is legitimate and grammatically correct.
My professor says that we're most likely using a "choice function" strategy to approach the factive sentences (know, regret, etc.) where you use the wh-word as denoting elements in a presuppositional set (i.e. "among the presents that Mary bought, which items does John know that Mary has bought?"). He compares this to another example, where you can say "who bought what?" but it's weird to say "what did who buy?", but by using the choice function strategy and making it denote a subset of a presuppositional set, you can say "which item did which person buy?" He said there are other theories to explain such phenomena, but that's his take on it.

Also, interestingly, in Chinese the verb "zhidao" for "to know" only has the possible interpretation of "John knows what Mary bought", not "What does John know Mary bought?" There are verbs, however, that don't have the same restriction as "to know", and since Chinese has no overt wh-movement, it can cause the sentence to have many interpretations that could be expressed in English with wh-movement. So with the verb "jide" or "to remember", for example, "John jide Mary mai-le shenme" (John remember Mary buy-ASP what) can be interpreted both as "John remembers what Mary bought" and "What does John remember Mary bought?"

Here's a more extreme example with the verb "gaosu" ("to tell") which can have FOUR different interpretations:
Zhangsan gaosu Lisi shei mai-le sheme
(Zhangsan tell Lisi who bought what)
1. Who is the person x and what is the thing y such that Zhangsan told Lisi x
bought y? (direct question)
2. Zhangsan told Lisi who is the person x and what is the thing y such that x
bought y. (indirect question)
3. Who is the person x such that Zhangsan told Lisi what is the thing y such
that x bought y? (direct question)
4. What is the thing y such that Zhangsan told Lisi who is the person x such
that x bought y? (direct question)