Consider this sentence:

You may worry about the Fed raising interest rates, or a market meltdown, but these risks should not change your investment plans.

Could the comma before "or" be omitted? I could argue no, because then the sentence would imply the reader may worry about the Fed "raising a market meltdown," which is clearly not the intent (A market meltdown is a separate risk). On the other hand, the phrase "raising a market meltdown" is clearly nonsensical, hence a comma may not be needed to clarify the writer's intent (the Fed could "cause" a market meltdown, but not "raise" one).

In other words, is it acceptable to omit a comma when its absence creates a syntactical ambiguity, but not a semantic ambiguity?


Rephrasing is usually the best answer to these kinds of cases. It's a made-up example. Assume the sentence as phrased is my best option, and my only decision is comma or no comma.

My understanding is this:

  • If a comma is optional, take it out.
  • However, if there is any possibility of ambiguity (without the comma), leave it in.

Ideally, I'm looking for an answer that cites an authoritative source (e.g. Chicago Manual of Style).

  • 2
    Honestly I think it just depends on personal preference/style. If, when you speak the words aloud, you find yourself pausing between "rates" and "or", I would leave the comma. If you find that there is no pause, remove it. I don't think it's more or less correct or acceptable either way.
    – EFrog
    Jan 11, 2015 at 16:15
  • I would rewrite the sentence so as to avoid the dilemma.
    – pazzo
    Jan 11, 2015 at 16:28
  • 1
    Why not leave the comma in? It's not incorrect, and makes the garden-path alternative easier to discount (you probably wouldn't even think of the thing). While dropping the comma is not 'wrong', it certainly might make some people have to think about the structure rather than the facts being reported for a second or two. Is that desirable? I'd probably give my custom to the newspaper / advisor using the more user-considerate style. How 'acceptable' would the commaphobic competitors find that? Jan 11, 2015 at 16:38
  • 1
    Just so you're restricting the change to the comma, you might want to change it to "Fed's raising" rather than "Fed raising"
    – idunno
    Jan 11, 2015 at 17:20
  • 1
    If you're interested in rephrasing, you could simply add another "about". Jan 12, 2015 at 6:31

2 Answers 2


Written English is governed by the principle "Anything which can be misunderstood will be".

There is thus no practical difference between a syntactical ambiguity and a semantic one: even if the ambiguity is resolvable with only a little effort, some readers will fail to make the effort and will either misunderstand your meaning or dismiss you as an idiot.

My own feeling is that it is your duty as a writer to make it as easy as possible for your reader to understand you, and as hard as possible for your reader to misunderstand you. If you can make your text more intelligible with a comma, put the comma in. If you don't like the comma, rewrite so it's not necessary:

You may worry about a market meltdown or the Fed raising interest rates, but ...

But as Edwin Ashworth points out, that has its own ambiguity: market meltdown may be taken as subject of raising. So:

You may worry about the Fed raising interest rates or the market melting down, but ...

  • Yes, I'm worrying about a market meltdown raising interest rates:-( And is the Fed related to the Fonz? Jan 11, 2015 at 16:41
  • @EdwinAshworth Ooh, good point -- QED! ... The Fed and the Fonz are both arrogant as hell, and have mysterious powers over incomprehensible mechanisms. Jan 11, 2015 at 16:48
  • 1
    re: making it as easy as possible for your reader, I agree a LOT. This includes (for me) not making me jump back a word or two to re-interpret as I scan through a sentence.
    – idunno
    Jan 11, 2015 at 17:23
  • 1
    @idunno Just after 'Don't abuse the word awesome ;-) Jan 11, 2015 at 17:31
  • 1
    @StoneyB It was idunno's sparkling ' re: making it as easy as possible for your reader, I agree a LOT. This includes (for me) not making me jump back a word or two to re-interpret as I scan through a sentence.' I intended nicking. That is, adding, with proper attribution, to my bank of variations on 'Be sensible'. Of course, J Lawler's 'It's grammatical, but that's about the only good thing you can say about it' heads the list. Jan 11, 2015 at 17:56

Can you see any hikers, using binoculars?

Can you see any hikers using binoculars?

Obviously, the comma is not 'necessary': both are grammatical. But the first sentence would usually be taken to mean

Using binoculars, can you see any hikers?

Whereas the second can either mean that, or

Can you see any hikers who are using binoculars?

Disambiguation is important (in speech here, emphasis/context would disambiguate).


Can you see any hikers with the unaided eye?

There is no scope for confusion. The comma is not needed to aid disambiguation. It might be used to signal a pause in speech:

"I don't need binoculars. I can see the distant Cascade Range with the unaided eye!"

"Really. But I'm unconvinced. Can you see any hikers, with the unaided eye? I can count about 20."

But otherwise, there is no reason to include it.


You may worry about the Fed raising interest rates, or a market meltdown, but these risks should not change your investment plans.

There is no cause for lasting confusion amongst people used to this terminology, as they would discount as illogical the alternative meaning. But other people not sure of financial jargon (does 'raise' have a subject-specific sense in finance, as it does with verbs?) might be confused, and even those used to the jargon might stray momentarily into the common 'doing A or B' reading. So not compulsory to include the comma here, but daft not to.

  • I once shot an elephant in your pyjamas.
    – Erik Kowal
    Jan 12, 2015 at 4:12
  • Why weren't you wearing your own pyjamas? I know, I'm supposed to think it was the elephant, but you flubbed the joke. Jan 12, 2015 at 6:30
  • @Brian Hitchcock No, this is the 15th amendment; you've missed the joke. Erik never forgets. Jan 12, 2015 at 11:02

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