How to determine whether an ambiguous sentence or phrase is syntactically ambiguous:
- Determine which readings the sentence or phrase has (paraphrasing helps).
- Check the syntactic category of each word in each of the readings. If one or more words has a different syntactic category in different readings, the sentence or phrase exhibits lexical syntactic ambiguity.
- Else, check the syntactic structure of the sentence or phrase in each of the readings (that is, draw tree diagrams; you may draw a partial tree involving only the ambiguous parts, if you feel confident enough). If the diagrams are different, the sentence or phrase exhibits structural syntactic ambiguity.
- Else, the sentence is not syntactically ambiguous (it may still be semantically, pragmatically, or otherwise ambiguous).
Note that what I just wrote resembles a recipe or a set of instructions for assembling a piece of furniture. By breaking down a complex process into a sequence of smaller, well defined and ordered steps, we are carrying it out through what is called an algorithm.
Practice exercise: Make sure you understand why the following
sentences exhibit the type of ambiguity indicated (follow the
algorithm if you don't).
- He saw her duck: lexical syntactic ambiguity (also structural, of course).
- I saw the man with the telescope: structural syntactic ambiguity.
- I drove into the bank: no syntactic ambiguity (in this case the ambiguity stems from the lexical semantics, or word meaning, of bank).