This morning, I used the phrase

I didn't sleep very well, I don't think.

when speaking to my Colombian friend and he asked me what on earth I was talking about.

I thought about it and realised that this is idiomatic usage and that despite saying "I don't think" you are actually expressing what you do think.

Generally the form is [expression of negative opinion using negative grammar] + "I don't think".

For example:

I didn't sleep very well, I don't think. => I think I slept poorly.

I won't get there very early, I don't think. => I think I will arrive late.

The first part is an opinion about what something is not, rather than what it is, i.e. my sleep was not good; my arrival will not be early. You wouldn't say:

I slept badly, I don't think.

It seems like "I don't think" is a way of intensifying the sentence, because it doesn't modify the meaning of the initial statement in any way. We seem to use it to express disappointment with a situation, but there might be more reasons.

  1. Is there a name for this usage?
  2. Do you use it to express anything other than disappointment?
  • As for your second question, I don't think it's confined to "disappointment." Consider: I won't be volunteering for that detail, I don't think (in other words, "Let some other sucker get roped into that"). Or: I won't be quitting my job anytime soon, I don't think (uttered by someone who likes their job).
    – J.R.
    Jan 7, 2015 at 11:21
  • @J.R. It is idiomatically correct, but in my experience nowadays unfashionable, perhaps because it can sound like a sloppy double negative. I tend to avoid it, unless the meaning is obvious, as it is in your second example, above. I would tend to say I don't think I slept very well last night.
    – WS2
    Jan 7, 2015 at 11:40

3 Answers 3


Maybe the answer is, they're two different sentences - but the second one is kind of truncated: "I don't think (so)". So, the second part is not attached to the first part, but reiterating the negative and confirming it.

  • 1
    I think there's some truth to that. In the example of I didn't sleep very well, I don't think, that second part might be expressing a bit of uncertainty, not disappointment. It's a shortened form of I didn't sleep very well; at least, I don't think I did.
    – J.R.
    Jan 7, 2015 at 15:14
  • I actually quite like this theory; I think William Bloom's link in his answer may confirm it.
    – Dog Lover
    Jul 26, 2017 at 9:46

It's called negation, albeit a special form of it used more in informal communication.

It doesn't express disappointment (although your tone when you say it might).

This statement...

I think Hillary Clinton will not run for president.

...is the equivalent of this statement...

I don't think Hillary Clinton will run for president.

...and a less formal, more idiomatic way of saying that is...

Hillary Clinton will not run for president, I don't think.

Notice this formulation combines the other two. It's technically a double-negative. It's fine face-to-face, but don't use it in formal communication.

Read more about negation at the following website. There's a section on negating "think" at the bottom.


Not … I don’t think

There are some cases where we can use reporting verbs such as imagine, suppose and think in end position, after the reported clause. In such cases, both clauses may have a negative verb:

He’s not a teacher, I don’t think. (or I don’t think he’s a teacher.)

Not: I don’t think he’s not a teacher.

I won’t be very late tonight, I shouldn’t imagine. (or I shouldn’t imagine I’ll be very late tonight.)

Not: I shouldn’t imagine I won’t be late.

Sometimes we use not in front position where a following reduced clause (a clause with something omitted but which is understood) also has a negative form:

A: Have you seen Leila?

B: Not today, I haven’t. (I haven’t seen Leila/her.)

A: Is Tony working at the university?

B: Not now, he isn’t. He used to.


The historical use of "I don't think" is to negate a previous disingenuous positive comment (often deliberately exaggerated) to highlight a deliberate irony.

It's exactly equivalent to: "You're a genius - not!"

The "pseudo double-negative" use is a common modern misuse of language by people who don't think about what they say.


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