“as long as” vs. “so long as”
Am I correct when I teach my students that “as long as” means you’re measuring time, and “so long as” means you’re using it as a conditional?
Hence, “I was here as long as he was” (meaning we were there for the same length of time) and “I will love you so long as you don’t cheat on me” (used for cause and effect situations)
"So long as" does not seem to be much used in the sense 'since.' The two are used pretty much interchangeably in the sense 'provided that' and in the more literal sense 'for the period of time that.'
http://books.google.com/books?id=2yJusP0vrdgC&pg=PA132&vq=so+long+as&dq=merriam+webster's+dictionary+of+english+usage&source=gbs_search_s&sig=K4iQZ9QcUE7byVjWREX_R_Q8vK4
John4 Apr-28-2008
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N.B.: Old English "swa" gets translated into Modern English as either "so" or "as." Personally, I use both expressions interchangeably. I see no semantic difference between them.
AO Apr-28-2008
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As John and AO indicated, the two constructions are essentially "co-existing variants" and mean the same thing.
My sense is that "as long as" is predominant but "so long as" continues to be used in various dialects. This is just a gut feel on my part however.
JJMBallantyne May-15-2008
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Oops! Forgot to add:
Both constructions are essentially idioms and interchangeable when used in the (conditional) meaning of "provided that."
But when we use "as long as" for comparison, it's not really the same expression. It is simply the comparative construction "as... as":
as long as
as big as
as easy as
as tall as
as difficult as
JJMBallantyne May-15-2008
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I find the variation useful for moving the stress in a sentence, since "so long as" is the less common. Compare:
"The new Severn Bridge is not as long as the old one"
with
"The new Severn Bridge is not so long as the old one"
The first version seems to be making a simple comparison of size, while the second seems to be making a qualitative observation about the length of the old bridge; without the context we can't tell if the speaker feels that more length is better or that the old bridge was over long.
Tolken Jun-09-2008
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So you may say "as long as" so long as you're measuring time?
anonymous4 Aug-15-2008
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they can be used interchangeably...
varun_verma_planman Dec-24-2008
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"The new Severn Bridge is not as long as the old one".
replace 'long' with any other "adjective" such as 'big', 'hot','ugly'.
as "adjective" as - is a comparison
so "adjective" as - does not make sense . ( So big , so tall...so is synonymous to very)
If you explicitly use the phrase 'compared to', then it makes sense.
"The new Severn Bridge is not so long,compared to the old one"
OR
"The new Severn Bridge is not so long" ( compared to nothing or in general or based off the context of a previous sentence , eg: "The old bridge is long".)
"The new Severn Bridge is not required as long as the old one does not fall"
Replace the "idiom" 'as long as' with 'so long as'
"The new Severn Bridge is not required so long as the old one does not fall"
RJ Mar-29-2012
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Growing up in Sydney in the 1950s and 60s, I rarely heard 'so long as'. 'As long as' was much more common. However, these days the reverse seems to be the case. The phrase 'so long', an informal way of saying 'goodbye', was very often heard in those days, especially in American TV shows and movies. Is it possible that the increase in usage of 'so long as' is a sub-conscious extension of 'so long'?
Geoff Lyons Jan-07-2013
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As nearly everyone has already said, when they mean "provided that" in a conditional - they are interchangeable.
But I don't quite agree about comparisons. In "as ... as" comparisons; "so" can replace the first "as" after "not", at least in BrE:
'After not, we can use "so ... as", instead of "as ... as". This is structure is more common than "less than" in informal English: "He's not so/as successful as his sister" '
(Practical English Usage - Michael Swan - Oxford)
So although I think I would usually say "as", it's quite possible to say "I haven't been here so long as he has". But in positive sentences only use "as".
Warsaw Will Jan-08-2013
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Regarding:
"...as "adjective" as - is a comparison
so "adjective" as - does not make sense..."
and to all others who suggest that using "so" in the comparative, non-conditional sense is somehow wrong:
I disagree. I certainly do hear "...so big as...", ...so tall as...", "...so as..." etc.
I would suggest there is a subtle difference in meaning. Tolkien and Warsaw Will are on the right track here.
"He's not as successful as his sister" simply means the sister is more successful than the brother.
"He's not so successful as his sister" similarly means the sister is more successful than the brother, but also means that the sister is very successful. The "as" version implies nothing about whether either is particularly successful.
if "so" is less common, it's not necessarily because it's wrong; it may simply be because the difference in sentiment it conveys is not as often needed or intended.
porsche Jan-09-2013
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According to Merriam-Webster Dictionary of English Usage, the "not so ... as ..." used to be the regular form in negative comparatives; it's "as ... as ..." that is the relative newcomer (for negatives). Jane Austen, while regularly using "as ... as ...." in positive comparatives, used "so .. as ..." in negative ones:
"She is not so pretty as I expected"
http://books.google.com/books?id=2yJusP0vrdgC&pg=PA124
This change in popularity of the two forms in negative comparatives is shown quite dramatically in this Ngram graph, with the "as" version overtaking the "so" version sometime in the1930s:
http://books.google.com/ngrams/graph?content=not+as+good+as%2Cnot+so+good+as%2Cnot+as+bad+as%2Cnot+so+bad+as&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=
Warsaw Will Jan-09-2013
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"She is not so pretty as I expected" sounds a little stilted to me.
"She is not as pretty as I expected" seems more natural.
user106928 Jan-09-2013
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It is difficult to find a difference between 'as long as' and 'so long as'. Both are inter-changeable. Still I often feel, while talking 'so long as' is used more than 'as long as' which is common in speaking and also writing.
Ram Pillai Aug-16-2013
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In case of comparison so long as is used as hatred expression&as long as is used in general
Tanvir Dec-11-2013
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@Tanvir - I'm not with you, could you give us an example?
Warsaw Will Dec-11-2013
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Thank you very much I 'm English teacher and I want to improve my language especially conversations how can you help me ? Thanks alot
Shaymaa awad Jun-07-2016
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"so long as" is used by people who are uneducated and repeat phrases they heard without thinking if those statements are logically or grammatically correct. "As long as" is the only correct phrase to mean "under the conditions of." This follows English grammar rules regarding comparisons, whereas the substitution of "so" for "as" is nonsensical since "so" is a qualifier.
user110719 Apr-01-2021
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