Take the sentence

Students who study physics rigorously learn math.

As it stands, 'rigorously' can modify either 'study' or 'learn'. But if we move the adverb to the front to get

Rigorously, students who study physics learn math.

'rigorously' unambiguously modifies 'learn' and not 'study.' This should be clear to any native speaker of English. However, when I think about it this phenomena, it's not clear at all why this must be the case. After all, might it not be more logical for the adverb to modify the closest verb? What are the (scientific) explanations of this sort of syntactic behavior?

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    In general, it doesn't. In some cases, it can. In this case, it's not clear that movement is improvement. How about "Students who study physics rigorously also learn math"? Adding a clarifying word, rather than making a random syntactic move, is more likely to help clarify. There are several issues here; is it possible to learn math in any other than a rigorous way? Not really; math is all about rigor. But engineering math is much more concerned with results and formulae, and knowing how to read scales and curves accurately. BTW, don't expect grammar to be "logical". Jun 12, 2015 at 1:58
  • @JohnLawler, naive set theory is non-rigorous math, as compared with axiomatic set theory. The differential calculus with infinitesimals was, classically at least, non-rigorous, as compared with the development based on limits of series.
    – Greg Lee
    Jun 12, 2015 at 2:14

2 Answers 2


The complex NP constraint, a grammatical principle discovered by John Ross, prohibits moving something from within a relative clause (RC) to a position outside the NP which contains the relative clause. So, starting from

[S [NP students [RC ... rigorously ] ] ... ]

to get to

[S rigorously [NP students [RC ... __ ] ] ... ]

would require breaking this constraint. However, starting from

[S [NP students [RC ... ] ] rigorously ... ]

moving "rigorously" to the beginning of the sentence does not break the law.

Thus, assuming the sentence is structurally ambiguous depending on whether "rigorously" is interpreted as part of the RC modifying "students" or not, the version with the adverb at the beginning could only have come from a sentence structure with the adverb outside of the RC.

John Lawler has a nice account of the Ross constraints on line -- see number 4 in his list.

  • God in Heaven!!
    – Fattie
    Jun 12, 2015 at 3:39
  • Looks like you got the answer you wanted. God help you if you actually try writing that way. Erik Kowal is rude, but dead on as to the uselessness of putting "rigorously" first. Jun 12, 2015 at 8:56
  • @BrianHitchcock God help you and Erik for completely missing the point of the question.
    – user118723
    Jun 12, 2015 at 9:14
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    You asked why moving it to the front removes ambiguity. There is no possible answer to that question, because it is based on a false premise. Why do pigs fly? Jun 12, 2015 at 10:19
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    Keep your eye on the ball, people. The question was not about grammaticality, and neither is my answer. The questioner was clear in describing the ambiguity he was concerned about, and my answer was qualified by the assumption that the ambiguity exists. I said in a previous comment that I don't find the sentence with "rigorously" in initial position to be normal English, personally. But this is just not relevant to either the question or my answer.
    – Greg Lee
    Jun 12, 2015 at 12:51

Moving the adverb immediately in front of the verb instead of the sentence eliminates the ambiguity, and also produces a structure that sounds like something a native speaker of English, and not a Martian, might generate **:

"Students who rigorously study physics learn math".

Incidentally, the assertion that in the sentence

"Rigorously, students who study physics learn math",

'rigorously' unambiguously modifies 'learn' and not 'study', is incorrect.

It doesn't modify either of those verbs (unambiguously or otherwise), because very few native speakers with normal cognitive abilities exist who would ever think of uttering (or writing) such a barbarism. Insofar as it can be said to modify anything at all, it modifies the entire sentence.

** Though the Martian would at least deserve some credit for effort.

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    Sorry, user118723, I'm with Erik here. An adverb + comma at the beginning modifies the whole sentence (cf. normally, usually, unfailingly, unequivocally, etc.). And "rigorously" modifying the whole sentence is without meaning. Jun 12, 2015 at 3:18
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    "I'm sorry, but I cannot agree with this." I'm tempted to make a really smart ass comment like "when you learn English, you'll agree with Erik" :)
    – Fattie
    Jun 12, 2015 at 3:36
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    @GregLee - It seems to me that you've misconstrued the nature of the OP's construction. It's not unacceptable as an example, it's unacceptable as an actual query sentence. This is because it is severely malformed in terms of Standard English usage, and is therefore incapable of making the kind of sense (whether grammatical or syntactic) that the questioner is attempting to impose on it. As for the tone of my answer: you feel it's gratuitously insulting, I feel it's humorously lighthearted. We'll have to agree to differ on this point.
    – Erik Kowal
    Jun 12, 2015 at 5:53
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    “It will be clear to any native speaker of English that in the second sentence, 'rigorously' modifies 'learn'.” ← No, it most certainly will not. As other comments have already shown, it is clear to many (I would venture pretty much all) native speakers that rigorously in the second sentence does not in any way directly modify learn, but the entire sentence. Jun 12, 2015 at 9:27
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    I agree with @Janus and Erik. There is a difference between "Rigorously, this theorem needs to be proved using prolate spheroidal wave functions," and "This theorem rigorously needs to be proved using prolate spheroidal wave functions," and that the second doesn't make any sense. (This is how rigorously is used as a sentence adverb.) Jun 12, 2015 at 10:25

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