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If vs. Unless

Express a particular condition for a desired outcome

Cooking
 

If vs. Unless

IF

An if phrase expresses that "an action or situation will happen after the other one happens first."  The action in the clause following if expresses (1) a condition for a singular outcome to occur; or (2) a recurring situation "whenever" with a predictable outcome (in general).

2ND ACTION 1ST  ACTION
DESIRED OUTCOME A PARTICULAR CONDITION

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.

 

DESIRED OUTCOME A GENERAL SITUATION

(+) You will always have a tender turkey

if / when / anytime / whenever you cook it slowly. (+)

(on multiple occasions; routine response; expresses timing or frequency)

UNLESS  "EXCEPT IF"

An unless phrase expresses "an action or situation will happen if the other one does not happen first" or "an action or situation won't happen if the other one happens first." Unless expresses "except if" or "if not" (See polarity¹, +positive or –negative wording.)

2ND ACTION 1ST  ACTION
+ / – OUTCOME + / – PARTICULAR CONDITION

(+) You will have a tender turkey

(–) You won't have a tender turkey

unless you overcook it. (–)

unless you cook right. (+) 

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.

DESIRED OUTCOME + / – GENERAL SITUATION

(+) You will have a tender turkey

You won't have a tender turkey

unless you overcook it. (–)

if / when / anytime / whenever you overcook it.  

(on multiple occasions; routine response; expresses timing or frequency)

 

¹polarity – words that are sensitive to the positivity or negativity of the surrounding words.  (if/unless, some/any, either, neither, already/yet, etc.)   See Positive & Negative Polarity,   Some / Any Polarity, Already / Yet Polarity, Too / Either Polarity.

if (P) – expresses the requirement for a particular situation to occur.     He will cry if you leave. (condition) 

if (P) – expresses the happening of a situation repeatedly. He cries if / when / whenever you leave.  (timing)   See if vs. when.    

overcook (V) – cook too much, past a desired state (a negative action).

recurring (Adj) – a repetitive or habitual situation that happens at regular intervals;  

reoccurring (Adj) – a situation that happens again but not repeatedly. 

 

 

 

 

If/Unless Clause or Phrase?

Understand the reclassification

 

If and Unless  in Traditional and Linguistic Description

TRADITIONAL TERM

Older grammar systems called if or unless 1) a conjunction because it added a clause with information to the main clause, or (2) an adverbial clause because it related a clause with information about the timing (how, where or when) of the verb in the main clause.

However, these catch-all terms failed to adequately describe how words like if and unless function in a clause. Also, the terms (descriptors) could not be applied universally to structures in other languages. Linguistic research came up with a system based on word meaning, function and category (shared properties) to meet this need.

CONJUNCTION / CONJUNCTIVE CLAUSE

Call me if you smell the turkey burning.   Relates information to clause. 

See "and" as a conjunction on And/In Addition page. 

Also see diagram: And, But, Or conjunction, exclusion, disjunction .

ADVERBIAL CLAUSE

Call me if you have time.  Relates information about timing of verb—When? 

See general term Adverbial.

Also more specific term Connective Preposition (Adjunct Preposition).

LINGUISTIC DESCRIPTION

The Cambridge Grammar of the English Language (2002) published some major changes to the category of Preposition (capitalized).

1) Prepositions have been widened to include words such as if, unless, before after, while, because, though, than, and as. Linguistic analysis determined that these words functioned more similarly to prepositions than to conjunctions, adverbs or other categories in which they had previously been placed.

2) Prepositional complements have been widened. A preposition is no longer limited to a noun as its "object".  A preposition may be followed by a word, phrase or clause.

PREP PHRASE – PREP + CLAUSE

Call me if you smell the turkey burning.  (clause)

PREP PHRASE – PREP + ADJ

 Call me if necessary[done, ready] (adjective) 

PREP PHRASE – PREP + ADV

You rarely call me, if ever. (adverb of frequency) 

PREP PHRASE – PREP + ___

See Prepositional Complements for words, phrases and structures that can follow other prepositions, besides (not including) if and unless.

 

See Connective Prepositions and Function v. Category.

Also see Grammar Notes below for grammar terms and see Conditional Summary for practices. 

 

 

 

 

If and Unless Phrase Positioning

Express emphasis by fronting the phrase

 

 

Emphasis Clause Order

STANDARD PLACEMENT

no commaNo particular emphasis is expressed when the if or unless phrase is placed after the main clause. A comma is not used.

NO COMMA

We'll bring some champagne if you wish.    

We'll bring some champagne unless you object.    

EMPHASIS PLACEMENT

commaEmphasis is expressed when the if or unless phrase is placed before the main clause. A comma separates the if phrase.

COMMA

 If you wish, we'll bring some champagne.

Unless you object, we'll bring some champagne.

 

 

 

 

 

If and Unless Timing

Relate the timing of the conditional situation

 

 

Tense—Present and Past vs. Future

PRESENT / PAST

When indicating present and the past routines, customs and habits, the tense of the clause following if or unless is the same as the tense in the main clause. (¹This tense agreement is also common with other connective prepositions such as before, after, when, etc. )

MAIN CLAUSE IF-PHRASE AGREES
PRESENT PRESENT

We often arrive at 8:00 

if our train is on time.

 

unless our train is late. 

PAST PAST

We often arrived at 8:00

if our train was on time.

 

unless our train was late.

FUTURE

When indicating future planned, scheduled or predicted activities in the main clause, a modal (will, may, can, should, etc.) is used; however, the verb in the clause following if or unless is marked with present tense.                                                                                  

MAIN CLAUSE IS FUTURE IF-PHRASE IS PRESENT
FUTURE PRESENT

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 our train is late. 

FUTURE *FUTURE

We'll arrive at 8:00

*if our train will be on time.

 

*unless our train will be late.

 

*incorrect usage.

¹ Note that this same tense agreement is true for other connective prepositions after, before, when, until, etc.  See After/Before/When or Time Related Events.

 

 

 

 

Only If 

Express emphasis with an auxiliary verb

Dishwashing
 

If vs If Only Subject-Auxiliary Inversion

IF

An if phrase placed before the main clause does not require a change in the normal word order of the main clause.

SINGULAR OR MULTIPLE SITUATIONS RESULT
ONLY IF + CLAUSE  SUBJ NP + VERB

If you dry your dishes with a towel,

they will be spotless!

If you use Zing dish soap,

you  get really clean dishes. 

If you used Zing dish soap,

you would get really clean dishes.

IF ONLY

An if only phrase placed before the main clause does require a change in the normal word order of the main clause. Ab auxiliary verb is required before the subject noun.

SINGULAR SITUATION RESULT
ONLY IF + CLAUSE  AUXILIARY – SUBJ NP – VERB

Only if you dry your dishes with a towel,

will they [will] be spotless!
  move forward

Only if you use Zing dish soap,

do you [do] get really clean dishes.
   move forward

Only if you used Zing dish soap,  

would you get really clean dishes.
  move forward 

 

 

 

 

 

If Only

Express a desired situation

 

 

A particular situation vs. a desire situation

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 (if only)  

If Only (Huddleston 751)  

 

 

 

 

 

Even if and Whether or not

Express that no condition will change the outcome

 

 

Even if and 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)

 

 

 

 

Otherwise, Else, Provided that

Express an action for success or failure with other expressions

 

 

If / Unless vs. Other Expressions

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.

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. (+)

 

If and unless express a condition when used for a particular (singular) occasion.  "this situation"

If and unless express timing when used for multiple situations (when, anytime, whenever). "the situation in general". See If v. When.

 

 

 

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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 to 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 condition as being satisfied 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 vs. if

subordinator  takes a clause as its complement

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

 

 

 

Works Cited

  • Azar, Betty Schrampfer, and Stacy A. Hagen. Understanding and Using English Grammar. 4th ed., Pearson Education, 2009.
  • Huddleston, Rodney D., and Geoffrey K. Pullum. The Cambridge Grammar of the English Language. Cambridge UP, 2002.
  • Lunsford, Andrea A., and Robert J. Connors. The New St. Martin's Handbook. 3rd ed., Bedford/St. Martin's, 1999.
  • Swan, Michael. Practical English Usage. 3rd ed., Oxford UP, 2005.

 

 

 

 

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.

 

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