Please consider the following sentence:

When cars collide, it creates a debris hazard on the road.

In a debate, I claimed the sentence is ungrammatical because the pronoun "it" has no antecedent. However, I was unable to find a rule in my 12th edition of the Gregg Reference Manual for "dangling pronouns."

The only noun in evidence is "cars," so the antecedent of "it" could, implicitly, be any one of the cars. The adverbial clause "when cars collide" could imply an instant in time, and "it" might refer to that time. However, I know of no rule that permits an adverbial clause to function as a noun.

Much more likely is that "it" refers to an implicit "collision," but there is no structure in that sentence that could even remotely serve as a concrete antecedent meaning "collision."

I lost my argument because I was unable to produce a grammar rule that disallowed the sentence. My opponent claimed that the meaning is clear. The meaning's being clear is a straw man, of course, irrelevant to the question whether the sentence is ungrammatical, but I lost the debate on votes.

My questions are, precisely:

  1. Is the sentence ungrammatical?
  2. If so, can one cite a rule that's violated?
  3. Can an adverbial clause function as a noun, and thus as the antecedent to a pronoun like "it?"
  4. If so, can one cite a rule allowing an adverbial clause to function as a noun? (ironic aside: I almost wrote "can one cite a rule allowing it," causing a nested instance of this very question).
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    It's a grey area. I'd use "... the collision creates a debris hazard." And the setup is so common, and I can do better, it's not worth fighting. Mar 3, 2022 at 19:19
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    "I just drove for eight hours. It was horrible." What is it? Mar 3, 2022 at 20:18
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    @PhilSweet Is it, though? I have no firm answer to this question (or else I'd give it), but seems to me we leave the antecedent implied by context all the time. "[The experience of driving 8 hrs] was horrible"; "[the collision] creates debris." Maybe this even gets into that nebulous existential "it" of "What time is it?" and "You look sad—what is it?" Mar 3, 2022 at 20:29
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    Having no antecedent doesn't make a sentence ungrammatical. The it in It's a long way to Tipperary has no referent, but it's not ungrammatical. Grammaticality is not caused by reference manuals, even Gregg. Grammaticality is what happens when people talk and understand without noticing what they're saying. Mar 3, 2022 at 20:32
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    First of all, ELU is concerned with usage, and there can be no rules to permit or prohibit usage. The question Is whether it is 'standard' English usage. Well, it is not inconsistent with it. Break them into two sentences. "Two/several cars collided. It created a débris hazard on the road." It not uncommon for a whole proposition/fact/event to be referred to by a singular preposition. "About thirty people tried to get on the metro at the same time and this caused several injuries. You could omit 'this', of course, but you can include it also. The meaning of the singular is obvious.
    – Tuffy
    Mar 3, 2022 at 21:53

2 Answers 2


I believe you have a simple case of the “dummy it” here. It doesn’t have an antecedent; it’s not meant to refer to anything.

Surely you would buy this as grammatical:

It’s bad when cars collide. (What’s bad when cars collide?)

And therefore this:

When cars collide, it’s bad.

Let’s try your sentence:

It creates a debris hazard on the road when cars collide. (What creates a debris hazard on the road when cars collide?)

When cars collide, it creates a debris hazard on the road.

We do this all the time. You can find some relevant results for when NOUN+ VERB , it VERB at the Corpus of Contemporary American English. (Click ALL FORMS (SAMPLE): 500 after the results appear to expand the examples.)

Here are a few spotted there:

And when Bruce surfaced, it surprised pretty much everyone.

When people meditate, it brings a certain sense of peace onto the campus that trickles out to other people.

When storms hit, it affects the righteous as well as the unrighteous.

When people volunteer, it helps their souls, it helps them socially, it helps them in business, and it helps the community.

Here are some the other way around it VERB NOUN+ when NOUN+:

It bothered Jerry when people acted strangely.

When you connect with a person and they say they’ll call you back, it produces anxiety when you realize (you’re) going to be gone for three days.

It made headlines when the most powerful member of the U.S. Senate clobbered America’s media giants.

She could see it angered Thang when Roi called her that, and Grandma's face would tighten whenever she heard Roi's callous laughter at Na's misfortune.

All that said, I think your sentence would sound better with a passive construction:

When cars collide, a debris hazard is created on the road.

  • In "And when Bruce surfaced, it surprised pretty much everyone." isn't "when Bruce surfaced" the antecedent of "it". Since there's not a strict requirement for the antecedent to actually precede the pronoun, the converse could be interpreted the same way. "And it surprised pretty much everyone, when Bruce surfaced." It seems a matter of interpretation/opinion though.
    – Stuart F
    Mar 4, 2022 at 12:45
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    @StuartF: I would call it an anticipatory it (antecedent) if it were used in this sense: It surprised everyone when Bruce surfaced. --> When Bruce surfaced surprised everyone. (They were surprised about the timing.) I would call it a dummy it if it were used in this sense: It surprised everyone when Bruce surfaced. --> When Bruce surfaced, it surprised everyone. --> (They were surprised that he surfaced.) Of course, with these being identical in form, you would need context to figure out what is meant. Mar 4, 2022 at 17:28
  • When cars collide, it (the collision) creates a debris hazard on the road. -- And when Bruce surfaced, it (the act of surfacing) surprised pretty much everyone. -- When storms hit, it (the storm's striking) affects the righteous as well as the unrighteous.
    – Greybeard
    Mar 7, 2022 at 17:14
  • @Greybeard: Yes, that is what is understood, but you had to make up nouns (the collision, the storm's striking, the act of surfacing) to give it an antecedent. Those aren't actually in the sentences. Mar 7, 2022 at 18:27
  • @TinfoilHat I see this as a valid referent by implication - The NPs are the action via the nominalised adverbial.
    – Greybeard
    Mar 8, 2022 at 12:28

It doesn't need a clear antecedent to be grammatical.

Many prescriptive grammar guides would consider that statement wrong. For instance, Towson University's Online Writing Support on "Usage - Pronoun Reference" says

A pronoun should refer clearly to one, clear, unmistakable noun coming before the pronoun. This noun is called the pronoun’s antecedent.

Then the site gives examples of "Errors" including too many antecedents, hidden antecedents, and no antecedents.

However, this approach addresses style rather than grammar. The site makes stylistic recommendations because students will often write sentences with confusing pronoun usage without any way to point or otherwise suggest what the pronoun refers to. Editors may impose such rules for similar reasons, avoiding bad writing by a blanket ban on usage likely to be misused. However, in terms of functional grammar (whether one understands what was just said or written without much thought), sometimes pronouns don't need antecedents to function well. For instance:

Mark called Mary's house all day, but she never answered the phone.

Absent some special context, she refers to Mary. There is no major issue with understanding that she refers to "Mary" rather than "Mary's house" or just "Mary's." Thus the sentence functions grammatically, despite the stylistic rule that Towson imposed.

Your example functions similarly. Most readers or listeners understand the sentence, including it, without much effort.

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    So @Reb.Cabin, you lose your argument if based on "grammaticality," but one could fabricate a scenario in which the pronoun is unwise and creates ambiguity. "This is the new robot model. Most of the time it's well behaved, but there are bugs. Whenever there's a big solar flare, it causes a lot of trouble for us." The solar flare poses trouble? Or the robot becomes troublesome? But as noted, these are issues of "style and usage"—i.e. *smart writing*—not grammar. Mar 3, 2022 at 21:58
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    @AndyBonner Nice examples. I must fight ambiguity all the time, at the risk of stilted writing. You would not believe the cunning ways that readers have of misinterpreting even carefully crafted technical material. I often do a pass over my own writing, driving out pronouns the way the Scots drove out the Vikings.
    – Reb.Cabin
    Mar 3, 2022 at 22:11
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    @DjinTonic LOL—clarifying Joyce sounds like a sisyphean punishment. Perhaps Joyce himself is at it even now. Mar 3, 2022 at 22:13
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    Like Summarizing Proust, Clarifying Joyce is a common competitive sport in England. Mar 4, 2022 at 4:11
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    @JohnLawler: Haha! Clarifying Finnegans Wake is a blood sport! Leaving many of those who survive the experience in a permanent state of post-traumatic stress disorder! Mar 4, 2022 at 13:05

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