What is the difference between I have seen people do it and I have seen people doing it?

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    – NVZ
    Jun 11, 2017 at 5:06
  • No different from do and doing. Jun 11, 2017 at 5:52
  • 2
    One assumes that the 'doing' has stopped in the meantime, but 'do' implies to a minimal degree that the action was punctive (eg dropping a piece of litter) and 'doing' that the action was more extended (eg sanding a wall with a pan-scrubber). Jun 11, 2017 at 8:16

1 Answer 1


The question focuses on "do" vs. "doing", but the issue is more complicated than that; it depends on the context.

In the gerund form, "I have seen people doing it", the gerund describes an uncompleted or in-process action. So this sentence implies that you actually witnessed the action.

The complication comes with "do", "I have seen people do it", which may or may not mean that you witnessed the action.

The sentence refers to past activity, so this usage of "do" is similar to using "did" -- it's a reference to the fact that it happened rather than a description specifically of witnessing the process of it happening.

Whether or not it's clear if the action was actually witnessed depends on the other verb, and whether that one is ambiguous. For example, "observe" means to watch (M-W), so if the sentence was "I have observed people do it", that would unambiguously mean you saw the action (it would probably be used with "doing", but that's a different issue).

Your example uses "seen" as the other verb. "Seen" has a lot of possible meanings. It can mean perceived by the eye, in which case you would have witnessed the action. It can also mean to come to know, which doesn't necessarily mean seeing it happen (see M-W). So "seen" doesn't distinguish the intended meaning.

If the sentence included a specific person, time, or place, that would imply the "witnessed" meaning of "seen". This sentence doesn't, just a generic reference to "people". So nothing else in the sentence clarifies the precise intended meaning (did the person witness the action or not?).

The use of "do" sets the stage for multiple potential meanings, and then it is a matter of the context provided by the rest of the text as to whether "do" vs. "doing" might have different intended meanings.

  • That should be that seen is the past participle not the past sense. The particular ambiguity you point out, if you want to call it one, is due to "people". Try it with a concrete person like "him" or "John". It becomes less clear to me that there's any difference. Some people would call this a participial (adjectival) use modifying the direct object, although certainly other analyses are possible. The important thing is that you create non-finite verb clauses either way, whether "I saw him do it" or "I saw him doing it".
    – tchrist
    Jun 11, 2017 at 21:49
  • @tchrist, interesting observation. I think you're right that "people" makes it more ambiguous. It's generally a more nebulous reference. But even with a specific person, I see the same kind of ambiguity. The gerund can't be ambiguous because of its continuing nature. But the ambiguity of "do" is tied to the other verb. "Seen" can be used literally or figuratively. If the verb in that place can be used figuratively, the sentence is ambiguous. So "do" vs. "doing" is only half of the story.
    – fixer1234
    Jun 11, 2017 at 22:25
  • "I've seen people texting and driving at the same time" Where's the ambiguity in that statement? Why would seen be a figurative reference? In order for it to be taken literal I should state where, the date, time of day, and the number plate of the car? It's just how normal people speak everyday. You're overreading this IMO. I don't see the ambiguity or that great a difference in meaning between that and "I've seen people text and drive at the same time" although I prefer the former.
    – Mari-Lou A
    Jun 11, 2017 at 23:38
  • @Mari-LouA, Some of the responses here and on the duplicate were that there is no real difference. To me, there's a clear difference of whether the meaning is that you witnessed someone doing it or you didn't. I agree that people talk that way every day. The ambiguity is in what they mean when they say it. The difference in meaning is what they question asks. I tried to explain the what and why in the answer. Is your point that I over-explained, or the question is too trivial to warrant a detailed explanation, at least on ELU (if this is migrated to ELL, the answer will go too)?
    – fixer1234
    Jun 12, 2017 at 0:06
  • @Mari-LouA, I was trying to understand your comment. My migration reference was because I originally thought this might be, and was writing more for an ELL audience. re: figurative issue--someone asks, "Do people ever paint their car purple?" If you've seen a few purple cars that looked like a poor paint job that someone did themselves, you might say, "I've seen people do it." That's a figurative use of "seen" because you didn't actually witness them apply the paint. My point was that interpretation is possible with "do" but not with "doing".
    – fixer1234
    Jun 12, 2017 at 0:19

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