I don't understand why we use Present Continous there, because the action has already ended, "they have already lied".

  • 1
    I think there's an implication that their dishonesty is permanent. You'd say "They were lying" otherwise, eg if they later told the truth.
    – Stuart F
    Jul 8, 2022 at 12:32
  • 1
    Perhaps because it concerns an ongoing situation. Jul 8, 2022 at 12:40
  • While you could say they lied, that addresses the past. Here, we may be stuck with their lie today. Not That wasn't true, but That isn't true. It's a lie. They're lying. Jul 8, 2022 at 13:45
  • If they are still speaking, and if they have not yet acknowledged their past lie, then they're still lying. Jul 8, 2022 at 17:30
  • Perhaps they were taped. Jul 8, 2022 at 19:04

3 Answers 3


"They're lying" is the most common way of expressing this concept in English. It's often a visceral statement. Unless there's more to the story that the person is about to explain, and some kind of past tense is needed so that the rest of the story will be clear, people are likely to deliver "They're lying" as the final, dramatic punch line, as in the example you included in your title.

I don't know how to document this -- sorry.


The continuous form of verbs always implies that the action is not complete at the time referred to.

With this in mind, the present continuous is appropriate as the speaker wishes to use this rhetorical device to imply that not only did the other person lie, but that they will continue to lie, i.e. their lying is not yet complete.

Were the speaker to have said "They have been lying!" It would allow for the possibility that, if challenged, the other person might start to tell the truth.


While it's clear that grammatically, 'They're lying' should have been 'They lied' or 'They were lying' or some other past tense, grammar is not the point.

'It's not true what they said…' sounds to me more like a fabrication for the sake of argument than anyone's real statement, still 'They're lying' would be the idiomatic response, because that's the way most of think, and speak.

In most cases - and I suggest this is one - idiom over-rides all the formal rules.

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