Consider the following quote, please:

You don't know what can happen tomorrow. Life is like a novel, isn't it? It's filled with suspense. You never know what's going to happen until you turn the page.” ― Sidney Sheldon (a well-known American writer)

In the bold sentence, wouldn't could be a better choice than can? To me, can is definite here and so doesn't sound good, while could in the sense of "maybe will" sounds better.

  • 1
    It's a close-run thing, but might (which I prefer) is actually more common than can or could here. In the end it's just a stylistic choice, but I agree with you that could is "better" than can for the "hypothetical" sense. Apr 19, 2020 at 17:59
  • @ FF, Thank you. You say: I agree with you that could is "better" than can for the "hypothetical" sense. By "hypothetical sense", do you mean the "maybe" sense of "could"?
    – Mr. X
    Apr 19, 2020 at 18:11
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    I just meant that could (and might) are better in your context because they're more strongly associated with hypothetical / unreal contexts, as opposed to the "ability" connotations of can. But to repeat - it's just a stylistic choice. Apr 19, 2020 at 18:26

1 Answer 1


It is grammatically correct, but it still seems the wrong thing to say.

Most people would normally say:

You don't know what will happen tomorrow.

What "will happen" tomorrow is definite, and most people would agree that you cannot see the future and know with certainty what will happen tomorrow.

What "can" or what "could" happen refers to possibilities. Lots of things could, or can happen tomorrow. Saying "you don't know what can happen" means the person doesn't even know any of the possibilities. Is that what you want to say? Most people would have a reasonable idea of what might happen tomorrow.

  • Thank you. Does "the could" in "you don't know what could happen tomorrow" have the same connotation as in "it could rain tonight"?
    – Mr. X
    Apr 19, 2020 at 18:37

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