I am confused in using tenses in sentences regarding thoughts:

I thought that it was interesting.


I thought that it is interesting.

Which sentence out of these two is correct and why?

3 Answers 3


Generally in this specific case, you'd want to make the tenses match.

I thought that it was interesting.

"Thought" is past tense, so "was" would be appropriate.

the past tense and past participle of think

You could certainly form the sentence in the present:

I think that it is interesting.

The difference here is that "think" is in the present tense, so the speaker is currently thinking that "it" is "interesting".

There are probably some constructions where mixing the tenses is appropriate. In fact, in this second example, it's fine with mixed tenses:

I think that it was interesting.

This means that the speaker is currently thinking that something was, at some point in the past, interesting... with the implication that it is no longer interesting.

One point of confusion may be that "thought" is both a verb and a noun. In this sentence, however, the use is as a verb. The noun version is countable, which means it would need an article, so if you wanted to use it as a noun, it would need to be rephrased considerably.

  • 1
    I can imagine the present/past case working with a few more words: "I think that it was [more] interesting [before ...]."
    – Phil
    Aug 31, 2015 at 23:09
  • Very true! @Phil Good point. I think that's easier with the present/past than with the past/present. Can you think of a version that might work in the case of the latter?
    – Catija
    Aug 31, 2015 at 23:10
  • I'm not able to make one. I think that the listener does not care if 'it' continues to be interesting, we are only concerned with the thought, which is said and done.
    – Phil
    Aug 31, 2015 at 23:27

Short answer:

"I thought that was interesting" is simplest and most natural.

Long answer:

The following are also completely correct and natural-

"I thought that is interesting --> I thought that's interesting"

"I thought that interesting"

"I thought, 'That's interesting'."

(also for mixed tenses- you can say in other situations:

"I think that was interesting" or of course "I think that's interesting" or "I think that is interesting".

You are also less likely to hear "that is" and more likely to hear "that's". "That is" sounds less natural. )

You could also say "I thought that is interesting" or "I thought that's interesting" if you were thinking in the past about a thing which is still interesting in the present. It would not be grammatically incorrect.

It would also sound natural to say "I thought, 'that's interesting'", if you're quoting yourself and making it sound like you're talking to yourself.


I thought that it was interesting.

is correct both grammatically and colloquially.

I thought that it is interesting.

is wrong and should never be used.

  • Technically true.
    – Lambie
    Sep 16, 2021 at 15:29

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