From what I've read on the Internet, there's a thing called The past open conditional. The person said that it is when you refer to an action in the past that you think happened or could happen, using an If-clause. So, the question is whether I can use it like in the example below or not.

If you started reading a book, read it to the end.

The sentence is supposed to mean that I'm almost sure that they've started reading it, and I advise them to read the whole book.

1 Answer 1


Open conditionals are used when the speaker thinks it possible that the "if" clause is true. You might use a past conditional when giving an instruction.

(teacher) Yesterday I gave everyone a book to read. If you started reading your book yesterday, please finish reading it now. If you didn't start reading your book, I want you to do a maths problem.

Or simple conditionals like

If you started reading your book yesterday, you know that the main character is called Paul.

Compare that to the "second conditional":

If you started reading your book right now, you would find out that the main character is called Paul.

Which presents an unreal situation (you didn't start reading) but is speaking about a non-past time.

The "first, second, third" pattern of conditionals is a simplification, to help learners understand that past tense in conditional expressions doesn't always refer to past time. But not every conditional expression fits this pattern.

Your example is, perhaps, not very common. But it is correct. It would be better to use a present perfect, as there is a strong connection to the present state:

I've you've started reading a book, you ought to read it to the end.

I've also put a modal in the advice, for extra clarity.

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