what does 'only' modify

[PrashantS209]

I have been reading that ONLY should be placed 'as close as possible' to what it modifies. Can it be placed on either side of what it modifies or does it need to be placed right BEFORE what it modifies?

Consider these sentences from GMAT Interact:
a) "..scholars could only guess as to how to translate hieroglyphics.."
b) "..scholars could guess only as to how to translate hieroglyphics..."

According to Noah, in sentence (a) ONLY modifies 'guess', so guessing is the only thing they could do (they could not know for sure)
in sentence (b) ONLY modifies 'as to how to translate hieroglyphics', so they could not guess about anything else. However, how do we know that only does not modify 'guess' as it is also close to 'only'? Or is the option (b) incorrect because it is ambiguous?

[Sage Pearce-Higgins]

Please could you give me a bit more information about the source of this problem? Which Interact lesson is it from and which problem does it relate to?

I would encourage you to be cautious about getting too deep into modifiers. This is probably the most complicated part of English grammar tested on GMAT; there are nuances and rules that are far beyond what you need to succeed on GMAT (and beyond what I know). I personally haven't memorized any rules for the use of 'only', but can reflect on my experience of English and the meaning of different phrases.

In the first example, the phrase 'only guess as to how to' means 'don't know how to' which has an appropriate meaning. In the second example, it sounds like the scholars can guess about the hieroglyphics, but can't guess about other things, which is a kind of nonsense meaning. Take a look at these example sentences and explain the meaning, saying if it's logical or not:

1) Dimitri only walks to work.
2) Dimitri walks only to work.
3) Amit could only guess how the new machine worked.
4) Amit could guess only how the new machine worked.

[PrashantS209]

Thanks Sage.

I can't remember which interact lesson it was from (or whether it was in the actual GMAT Interact) but recently came across it in the GMAT Interact demo (https://www.manhattanprep.com/gmat/prep/on-demand/). If you select VERBAL when he asks which section you are most concerned about, then he uses the problem I used in my first post.

[Sage Pearce-Higgins]

Thanks for the link. I've taken a look and I agree with Noah's approach to modifiers: he emphasizes the skill of seeing how the meaning changes for different positions of the word 'only', but doesn't encourage you to memorize any complicated rules. That's how I'd recommend you approach modifiers.

In answer to your earlier question about the position of 'only', look at the above examples and see if you can work out if 'only' is situated before or after the thing that it modifies.