When is 'unless' used?

Question

I will not finish my work in time because you do not help me.

Can I rewrite the sentence by using 'unless' as the following?

Unless you help me, I will not finish my work in time.

Is it true that 'unless' is not used when the meaning is more like 'because ... not'?

It should be "on time." "Unless you help me, I will not be able to finish my work on time." Incidentally, you're first sentence sends a little weird to me. Or rather, it's quite direct and almost rude, depending on your relationship with the person. And I didn't understand your question. I think you put in an extra "not." — Teacher KSHuang, Jan 09 '17 at 07:47
@TeacherKSHuang "In time" is perfectly acceptable. "I don't want to miss the train. I hope i make it to the station in time." — verbose, Jan 09 '17 at 08:25
There's no indication in the OP's question that the example sentences refer to a deadline. "I want to take the 6pm train. To catch that train, I need to finish my work and leave for the station by 5:30. However, I will not finish my work in time because you don't help me." — verbose, Jan 09 '17 at 08:42
@theinlewin That rule (or whatever they call it) probably originates from Practical English Usage by Michael Swan. One of his examples is good, **I'll be surprised unless the car breaks down soon. We wouldn't use unless* like this. But it looks like the rule is a bit overgeneralized. And this is more about semantics than syntax. FWIW, I like Araucaria's explanation here: My wife will be angry, unless I'm home by 7.00. — Damkerng T., Jan 09 '17 at 09:53

verbose · Answer 1 · 2017-01-09T08:49:05.673

Your understanding is correct. "Unless" cannot be used to replace "because ... not". It is logically equivalent to "if ... not". Your second statement means:

If you do not help me, I will not finish my work in time.

In other words, "unless" refers to conditional or hypothetical situations, not actual ones. When you're stating an actual fact—the reason X happens is that Y doesn't happen—you cannot use "unless".

The Education First site has a fuller list of examples showing how "unless" is the equivalent of "if ... not". Off the top of my head, I can't think of any equivalent one-word replacement for "because ... not".

Oh, heh, duh, after reading your response, I understand the original question. — Teacher KSHuang, Jan 09 '17 at 08:37

score 1 · Answer 2 · answered Jan 09 '17 at 09:36

I will not finish my work in time [because you do not help me].

[Unless you help me], I will not finish my work in time.

The underlying meaning of both examples is similar: in order to finish my work on time, I will need your help. But the grammar is different.

In 1. the bracketed element is a reason adjunct. It gives the reason that you will not finish your work in time.

In 2. The bracketed element is a conditional adjunct. “Unless” means “except if”. The adjunct could be replaced with if you don’t help me with no change of meaning.

When is 'unless' used?

2 Answers2