[Source:] !! Do not use the future tense after unless
[✓] I won't go unless you go
[✘] [I won't go] unless you will go. [✘]

Why not? Even if the above is prescriptive, what may be some reasons? In my separate question here, I quote: unless = if not. If not can precede future tense; so why can't unless?

Footnote: This Wordreference.com question motivated this.

  • "Unless" does not equal "if not". If it did, you could grammatically replace "if not" in the good sentence and have it be correct, but it is not. "I won't go if not you go" is not good grammar. Please explain here why you think they are equivalent and an example of such.
    – Catija
    Commented May 1, 2015 at 4:00
  • @Catija Please confirm if you read linguistics.stackexchange.com/q/12238/5306 (As linked above)? I adduced 2 books on logic there about this. Please advise whether I ought to adduce them here too.
    – user8712
    Commented May 1, 2015 at 4:02
  • 5
    If you're going to ask a question here, you shouldn't require that someone go to another page to actually see the content of the question. This question should (in my opinion) be able to stand on its own. Also, your own source doesn't say that "unless" is equivalent to "if not" it says "if ... not" the "..." is important, as it means that something comes between the "if" and the "not".
    – Catija
    Commented May 1, 2015 at 4:08
  • 1
    It's not actually true, though most of the time it would be semantically odd to include will. I can't understand the part about if not preceding will.
    – user230
    Commented May 1, 2015 at 7:15
  • See my answer to your other question about "unless".
    – TimR
    Commented May 1, 2015 at 13:59

2 Answers 2


The premise of your question is wrong. This is because there is no future tense in English. We can refer to future time in many ways. One way is to use the simple present, as in:

1 Unless I see the money on my desk by tomorrow 9am, you're a dead man.

The modal will can also be used to refer to future time. This seems to be the construction you're asking about, so I'll bold an example:

2 Unless they will agree to paint the house red, do not hire them.

(It has been stated that "(this usage of will) is not exactly about the future; it's about volition, i.e. "will" (or willingness)." To which, I reply that as uttered by someone, I am not sure we can neatly cleave willingness and referring to future time. I will go with you is expressing one's present willingness to perform the stated action in the future). Even so, I offer another example:

3 Unless they'll go to see Star Wars tomorrow, I'm not going with them.

But so can about ten other constructions, including these common ones:

4 Unless I am seeing the money on my desk in five minutes, you're a dead man.

5 Unless you are going to tell me the real reason, don't bother to open your mouth.

6 I don't want to bother you for a ride to Boston, unless you'll be driving there anyway.

7 Unless you're about to leave, don't bother washing the car windows.

8 We're going to have way too much work to do unless you are to come to your senses and hire some temps.

(Granted the last construction {to be plus to} is rather stilted and part of 'old school' business language.)

Edited to add:
Other examples of present progressive to refer to future time:

9 Unless I'm sitting here and hearing the sound of your feet walking up the stairs to my office in five minutes, don't bother to come.

10 You can't have any unless you're doing your homework in five minutes.

Also note the response to the question Can I have some candy?:

11 No you may not. Not unless you're doing your homework in five minutes.*


  • 2
    "Unless I am seeing the money..." is not right. It should just be "Unless I see the money...".
    – Catija
    Commented May 1, 2015 at 14:27
  • 1
    No, the present progressive can be used to 'stretch out' the moment indicated by the simple present.
    – user6951
    Commented May 1, 2015 at 14:35
  • 5
    Um... as a native AmE speaker, I'm telling you, it sounds like something a person who doesn't speak English natively would say. It is not natural English, regardless of what your book might say. Oh, and I went to UT, too :)
    – Catija
    Commented May 1, 2015 at 14:43
  • 1
    @catija is quite right. pazzo, your example in the comment sounds natural because "You're doing your homework" sounds natural on its own. "I'm seeing the money", on the other hand, does NOT sound natural on its own. It's not something a native speaker would say. They would say "I see the money". That's why "unless I see the money..." sounds right, and "unless I'm seeing the money..." sounds wrong. And believe me as another native speaker—it DOES sound wrong. This sort of construction is NOT becoming more common. (Also, there's is no "book of English")
    – user428517
    Commented May 1, 2015 at 17:10
  • 1
    @sgroves But that is how English is actually used! I can't help that it sounds weird and/or unnatural to a certain portion of the English speaking world. (And, overall, in my answers, I try to distinguish between merely grammatical correctness and actual usage.)
    – user6951
    Commented May 1, 2015 at 18:24

We can say:

Don't bid on the Cezanne unless you see me tugging on my earlobe.

The clause that follows unless must be an assertion against which the relevant circumstances can be compared.

A statement in the future tense does not express a valid condition; we cannot measure the present against the future; conditionals do not work that way.

Don't bid on the Cezanne unless you will see me tugging on my earlobe. [not ok]

Don't eat the seafood if it is spoiled.

*Don't eat the seafood if it will be spoiled. [makes no sense]

Don't eat the seafood unless it is fresh.

Don't eat the seafood unless it will be fresh. [not ok]

P.S. These present tense assertions in conditional contexts act as booleans. A statement about the present is reducible to true or false:

He is wearing a black hat. (true or false?)

But a statement about the future is essentially a prediction, and predictions cannot be reduced to true or false.

He will be wearing a black hat. True or false? (the question is "off")

When setting conditions, we can refer to:

the present (unless he is wearing a black hat)
the past (unless he was wearing a black hat)
and the past as seen from the point of view of the present (unless he has been wearing|has worn a black hat)

If we say "unless he will wear a black hat, don't cast him as the villain", will is not a future but means "unless he agrees|is willing to wear a black hat". The statement becomes possible when we take will to have a present-tense meaning.

P.P.S. There is a difference between will and is going to here. If you listen to native speakers speaking, they choose is going to over will after unless.

The present tense makes the predicate reducible to a boolean true/false.

You won't need your umbrella, unless it is going to rain. idiomatic
You won't need your umbrella, unless it will rain. unidiomatic

  • Thanks. Would you please explain how why we cannot measure the present against the future ? How do conditionals not work that way ?
    – user8712
    Commented May 13, 2015 at 0:41
  • Will you please to respond in your answer, which is easier to read than comments?
    – user8712
    Commented May 13, 2015 at 0:42
  • You cannot decide until you reach the fork in the river.
    – TimR
    Commented May 13, 2015 at 10:15

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