Study materials
None of these sentences has an if clause, yet each contains a condition.
But for her warning, we would have missed the deadline.
Say one word to him and he'll tell everyone.
She warned us. Otherwise, we would have missed it.
This article explains but for, without and with, the imperative with and or or as a condition, otherwise and or else, and would with no condition stated.
But for and without
But for and without squeeze a whole condition into a few words. They are followed by a noun, not a clause with a verb. They name the thing without which everything would have been different, so the main clause needs would.
But for the delay, we would be home by now.
Without your help, this would have taken weeks.
With a bit more time, we could finish it.
If we had a bit more time.
But for sounds more formal than without and means the same as if it weren't for or if it hadn't been for. With and will give a real condition: With a little luck, we'll win.
The imperative as a condition
The imperative, the form of a request or order such as book or hurry, together with and or or also expresses a condition. It is common in speech and advertising.
Book now and you'll save twenty percent.
If you book now, you will save.
Hurry up or we'll be late.
If you don't hurry, we'll be late.
A noun can stand instead of the order: One more mistake and you're out. And introduces the result of a condition that is met, or the result of one that is not. Or else means the same as or. Otherwise also means or else, and it comes after a comma, a semicolon or at the start of a new sentence.
Take a map, otherwise you'll get lost.
She warned us. Otherwise, we would have missed it.
Otherwise, that is, if she hadn't warned us.
Would with no condition stated
Sometimes the condition is not named at all. Would in the sentence shows that there is one, and the reader fills it in.
I wouldn't say that.
If I were you, I wouldn't.
That would explain the delay.
If that is true, it explains the delay.
That is why would is so frequent in diplomatic and business language. It lets you give an opinion more softly than a direct statement.
Common mistakes
The first mistake is a main clause without would after but for.
But for her warning, we missed the deadline. → we would have missed the deadline.
Without would it becomes a story of what happened.
The second mistake is and instead of or.
Hurry up and we'll be late. → Hurry up or we'll be late.
With and, hurrying would cause the delay.
The third mistake is a clause with a verb after but for.
But for she warned us, we'd have missed it. → But for her warning, we'd have missed it.
But for takes a noun.
The first mistake shows in the main clause. Without would, could or might the condition disappears. The second shows when you ask what follows the order. A good result is introduced by and, and a bad one, if the order is ignored, by or. The third shows right after but for. A noun such as her warning or the delay goes there, not a subject with a verb.