Sorry if this question is too simple. Someone wrote a sentence in which he used the word "alacrity" and asked whether he used it correctly. A native speaker replied:

I have a feeling many people could not define alacrity.

Does "could not" sound natural here?
I know that "could" can be used when we are not completely certain about something or to talk about a future possibility but isn't "could" in "people could not define" referring only to the past?
I would expect "people would not be able to define".

  • 5
    It sounds perfectly natural. The continuation 'if they were asked to' is implied, so it is a conditional. Commented Nov 26, 2021 at 17:38
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    ...and so it is referring to the future, not the past, and there is a clue in "I have a feeling". When referring to the past, a possible sentence is "I found that many people could not define alacrity." Commented Nov 26, 2021 at 17:40
  • @Kate Bunting I agree that this sounds natural, but disagree that there is any implied conditional. It is a different sense of "could" meaning simply "to be able to" and need not have anything to do with any conditional statement. See my answer. Commented Nov 27, 2021 at 1:41

1 Answer 1


"Could" like many basic words, has a wide range of meaning.

I suspect that many people could not [do] X.

pretty much means

I suspect that many people are not able to [do] X.

This is distinct from the senses of "could" referring to future possibility.

Some examples:

  • A human could not live for more than a few minutes in a vacuum.
  • A normal ten-year-old could easily understand thsi concept.
  • An adult elephant could easily pull a two-ton load.
  • A writer could include both first-person and third-person sections in a novel.
  • An airplane could not function where the air is too thin.

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