Grammar-QuizzesConnectorsAdjunct PrepositionsConditionals › If vs. Unless

If vs. Unless

Express specific conditions for an outcome

Cooking
 

 

If / Unless

IF

A conditional sentence with if expresses "An action or situation will happen after the other one happens first."  The action in the clause that follows if is the action required before the desired outcome in the main clause can occur.

2ND ACTION 1ST  ACTION
DESIRED OUTCOME REQUIRED CONDITION – IF

You will have a tender turkey

 if you cook it slowly.

You will have a tough turkey

if you overcook it.

We'll arrive at 8:00

 if our train is on time.

We'll bring some champagne    

if you wish.

UNLESS 

A conditional sentence with unless expresses "An action or situation will happen if the other one does not happen first."  The action in the clause that follows unless is the action that cannot occur for the desired outcome in the main clause.

2ND ACTION 1ST  ACTION
DESIRED OUTCOME ADVERSE CONDITION

You will have a tender turkey

unless you overcook it.  

"except if"

You will have a tough turkey

unless you cook it slowly. 

We'll arrive at 8:00 

unless our train is late.

We'll bring some champagne  

unless you object.

 

adverse (Adj) – not favorable, in opposition (bad)

if — heads an adjunct prepositional phrase that takes a clause (and a few other word forms) as its complement. The condition "clause" is actually a prepositional phrase (PP). Call me if you are ready. Call me if necessary. I rarely, if ever, call them.

See Conditional Summary of Practices. 

 

 

 

 

 

If / Unless Clause Position

Punctuation

 

 

 

Emphasis Clause Order

EMPHASIS PLACEMENT

commaThe if or unless phrase can be placed before the outcome clause for emphasis.  A comma is placed after the if phrase.

COMMA

 If you wish, we'll bring some champagne.

Unless you object, we'll bring some champagne.

STANDARD PLACEMENT

no commaWhen the if or unless phrase is placed after the main clause, no particular emphasis is intended, and a comma is not used.

NO COMMA

We'll bring some champagne If you wish.
   

We'll bring some champagne unless you object.
   

 

 

 

 

 

 

 

If / Unless

Tense Agreement

 

 

 

Tense Use

PRESENT / PAST

When discussing habits or routines, the present or the past tense can be used in conditional statements. See Pres-Past Conditions.

IF

We often arrive at 8:00 if our train is on time.

We often arrived at 8:00if our train was on time.(routinely)

UNLESS

We often arrive at 8:00 unless our train is late

We often arrived at 8:00unless our train was late. (routinely) 

FUTURE

However, when discussing future plans, the present tense is used for the future in the unless or if condition.

 IF

We will arrive at 8:00 if our train is on time

 

*We will arrive at 8:00 if our train will be on time. (use present)

 UNLESS

We'll arrive at 8:00 unless our train is late.  

*We'll arrive at 8:00 unless our train will be late.  (use present)

 

*Yellow highlighting marks an example with incorrect usage.

 

 

 

 

 

 

Condition

Condition for success vs. likely failure

 

 

 

Condition for Success vs. Failed Outcome

IF / UNLESS

An if phrase poses a condition in order to achieve an outcome: if, only if, unless , provided that.                                                                                            

ONE WAY (OTHERS MAY EXIST)

If you use a thermometer,  you will know when your turkey is done.

ONLY ONE WAY

Only if you use a thermometer, will you know when your turkey is done.  (auxiliary verb goes before subject)

NOT DOING IT THIS WAY  (– / +)

Unless you use a thermometer (+)  you won't know when your turkey is done. (–)

OTHER EXPRESSIONS

In contrast, the outcome of an otherwise or an or else phrase states the likely outcome if you do not do  the action in the clause or sentence before it.

ONE WAY

Use a thermometer. Otherwise, you won't know when your turkey is done. (Otherwise is followed by an independent clause)

ONE WAY

Use a thermometer, or else you won't know when your turkey is done.

SPECIFICALLY THIS WAY

Provided that you use a thermometer, you will have a delicious turkey. (+)

 

 

 

 

 

 

 

Only If

Word Order — Transposition

Dishwashing
 

 

Beginning with Only if

CONDITION

Both an if and an only if phrase may be placed at the beginning of a clause. A comma separates the prepositional phrase with the condition from the main clause.

IF

If you dry your dishes with a towel,

If you use Zing dish soap,

If you used Zing dish soap,

ONLY IF

Only if you dry your dishes with a towel,

Only if you use Zing dish soap,

Only if you used Zing dish soap,  

OUTCOME

Note that he outcome of the only-if phrase has the auxiliary verb placed before the subject.                                                                                                              

STANDARD WORD ORDER

      they will be spotless!

      you  get really clean dishes. 

      you would get really clean dishes.  (conditional)

TRANSPOSED

will they [will] be spotless!
  move forward

do  you [do] get really clean dishes. (get = do get)
  move forward

would you [will] get really clean dishes.
  move forward 

 

 

 

 

 

 

 

Commonly Confused

Only if / If only

 

 

 

A Condition vs. A Wish

ONLY IF

Only if expresses that one condition is required to achieve a desired effect. When used at the beginning of the sentence the auxiliary verb is moved before the subject. Only is a focusing adverb for if which is a preposition.                                                                       

ONE CONDITION

Only if  you dry your dishes with a towel, will they be spotless!

Only if  you clean up your room, will you find your lost jeans.

Your windows will be clean enough to see your face only if  you wash them with Zing!

I will please my mother-in-law only if my house is clean.

I am happy only if you are here. / Only if you are here, am I happy.

She was pleasant only if we told her what she wanted to hear.
  

IF ONLY

If only expresses a wish—one that you are doubtful about actually happening.  The result clause is optional and is separate. It is more emphatic than I wish…  If is a preposition and only is a focusing adverb for the content of the clause that follows.

I WISH…

If only  I had more time!   I could relax.   

If only  you would clean up your room. You would find your lost jeans.  

If only I had some Zing window cleaner.  

If only  I could please my mother-in-law.

If only  you were here! 

If only  he hadn't told his mother everything. 

 

Also see Wishes (only if / if only)  

If Only (Huddleston 751)  

 

 

 

 

 

 

 

Commonly Confused

Even if / Whether or not

 

 

 

Even if & Whether or not

EVEN IF

Even if expresses that something is a challenging or negative condition.  "No condition will change the outcome"  Even if emphasizes the speakers intent to achieve the outcome or goal without regard for a difficult or negative condition. [Focus Adv + Prep]                                        

OUTCOME CHALLENGING CONDITION

I'll help you

even if I don't have much time. 

I like to walk to work

even if it is raining.

Your father loves you

even if your father doesn't say it.

He'll get his work done

even if he has to work all night

 

WHETHER OR NOT

Whether or not expresses that no condition (or its alternative) will stop the completion of the outcome in the main clause. That is, if the condition exists or if the condition does not exist, the outcome will or must happen anyway.  Also called an exhaustive conditional.

OUTCOME THE CONDITION DOESN'T MATTER

I'll help you

whether or not I have much time.

I like to walk to work

whether it is raining or not .

Your father loves you

whether or not he says it.

He'll get his work done

whether or not we wants to work all night.

 

Whether can be split apart from or not by the subject and predicate of the clause. 
See  If / Whether.

alternative (N) – something you can choose to do or use instead of something else
Also see  even if  Adverbs for Emphasis

(Huddleston 8 §14.1.3, 11 §5.3.6)

 

 

 

 

 

 

► Show Grammar Notes and Resources? ▼ Hide Grammar Notes

Grammar Notes(Advanced)

Traditional and Linguistic Descriptions

 

 

Traditional  and Linguistic Descriptions

TRADITIONAL and ESL GRAMMAR

if, unless

If-clauses (also called "adverb clauses of condition") present possible conditions. The main clause expresses results.  (Azar 17-6)

Words that introduce adverb clauses of condition (if-clauses)  if, whether or not, even if, in case, only if.

true condition  If you tell me about the problem, I will help. (True in the present or future)

untrue condition If you had told me about the problem, I would have helped. (Information in the if clause is contrary to fact.)

subordinating conjunctions  introduce adverb clauses and signal the relationship between the adverb clause and another clause, usually an independent clause.  (Lunsford 147) (Swan 257)

Conditional sentences introduced by if, focus on questions of truth. Conditional sentences "make different assumptions about the likelihood that what is stated in the if clause is true, and then draws the corresponding conclusion in the main clause." (Lunsford 710)

Unless  "if…not"

means if…not (Azar 17-10)

has a similar meaning ot if…not , in the sense of 'except if". Come tomorrow, unless I phone. (Swan 601)

if, whether

"When a yes/no question is changed to a noun clause, whether or if is used to introduce the clause. Whether is more common that if in formal English . Both whether and if are commonly used in speaking."  (Azar 12-3)

I don't know [whether he will play].  "noun clause" 

[Whether or not he will play] is unclear.  (Azar 12-3)

 

LINGUISTIC DESCRIPTION

if, unless

preposition.conditional adjunct subordinator 

preposition heads an adjunct prepositional phrase that takes a clause as its complement

if [ protasis (the proposition, the condition) + apadosis (the answer, consequence)]    (Huddleston 8 §14)

open conditional  If he lies, everyone will know.  If P (then) Q.

remote conditional  If he lied, everyone would know. P ≠ true. Q ≠ true.

The remote construction differs from the open in that it entertains the condtion as being statisfied in a world which is potentially different from the actual world." (8 §14.2.1)

Unless  "except if"

Unless occurs in open conditionals and less frequently in remote ones. (8 §14.3)

We'll be there on time unless there is traffic. (open)
I wouldn't say I would be there unless I could. (remote)

Unless does not replace "if not". (Huddleston 756)
We'll leave now unless you'd rather wait. "except if"
*We'll leave now if not you'd rather wait.

whether v. if

subordinator  takes a clause as its complement

They are sometimes interchangeable but not always.  (Huddleston 11 §5.2)   See Subordinate Yes/No Questions.

 

 

 

Resources

  • Azar, Betty Schrampfer, and Stacy A. Hagen. Understanding and Using English Grammar. White Plains, NY: Pearson Longman, 2009. Print.
  • Huddleston, Rodney D., and Geoffrey K. Pullum. The Cambridge Grammar of the English Language. Cambridge, UK: Cambridge UP, 2002. Print.
  • Lunsford, Andrea A., and Robert J. Connors. The New St. Martin's Handbook. 3rd ed. Boston: Bedford/St. Martin's, 1999. Print.
  • Swan, Michael. Practical English Usage. 4th ed. Oxford: Oxford University Press, 2009. Print.
 

 

 

 

 

 

 

Practice

Road Rules 

wheel change
 

 

Complete the sentence with the conditional connector that is logical (+ / -).

  1. Select the response from the list that best completes the sentence. 
  2. Compare your response to the feedback by clicking the "check" button.

 

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.