Me: So what did you guys do in history class today?
Adam: We had a debate on which was more effective, Progressives or Populists. I argued for Populists.
Doug: Why did you say Populists were more effective?
Adam: Because I was sitting on the left side of the room, and Mr. Ridgway said that people on the left would be–
Doug: Wait, what I meant was—
Me: Ha! An attachment ambiguity involving an extracted adjunct! Nice!
Doug: –what reasons did you give for why Populists were more effective?
Adam: Oh! Because they drew from a lot of parties: Socialists, Marxists, and others. Also, they paved the way for the Progressives like Woodrow Wilson…
While Doug and Adam continued their conversation, I thought about the question Doug had intended to ask Adam:
The WH adverb Why at the beginning of the sentence has a subscript 1, indicating that it corresponds to the GAP category on the other side of the diagram. This GAP category appears where it does because that’s where you’d expect an explanatory phrase or clause to appear, such as because they drew from a lot of parties: Socialists, Marxists, and others. A clause like that basically takes the entire sentence Populists were more effective and turns it into a bigger sentence, which is shown by the lower S node spanning Populists were more effective, and the upper S node spanning both that and the GAP category.
The connectivity between the WH words and the gap is informally called extraction. I’m deliberately avoiding calling the gap an adverb or adverb clause, though, because I’m reserving the term adverb to refer to words such as confidently, never, and fortunately. To refer more generally to adverbs, adverb phrases, prepositional phrases and subordinate clauses that modify verb phrases or sentences, syntacticians typically use the term adjunct. Hence my appreciative remark about an extracted adjunct.
Anyway, here’s the question Adam took Doug to be asking:
The words are the same, but this time the GAP category takes the inverted sentence did you say Populists were more effective and make a larger Sinv out of it, as you can see by the stacked Sinv tents. It’s looking for an answer to the question of why Adam said what he said; in this case, the answer was that the teacher just divided the class down the middle and had one side take one position and the other take the other.
Although in English, extracted adjuncts can give rise to ambiguities like this one, some languages mark the difference overtly. For example, if we had conducted our conversation in the Mayan language Kaqchikel, instead of containing an inaudible gap, the question would have had the particle wi to show where the adjunct took scope, kind of like this:
- (Doug’s intended question) Why did you say Populists were-wi more effective?
- (Adam’s interpretation) Why did you say-wi Populists were more effective?
Alas, we weren’t speaking in Kaqchikel, so we just had to rely on context, which in this case gave insufficient clues.
Update, Oct. 16, 2016: Added some clarifying details.