First of all, this is not a duplicate... E.g., have a look at these posts:


"as ... as" or "so ... as" for comparison?

Anytime people on those posts talked about the use of 'so...as...', they said either that it can be used 'only in negative context' or that it can be used 'only with negative comparatives'.

Well, it is not clear to me at all what is meant by 'negative context/comparatives'... I am quite sure there was something significant omitted in the explanations. E.g., look at the following sentences:

Like the coordinating conjunctions, it is perfectly fine to begin sentences with because, so long as you keep in mind that the goal is to avoid fragments.

(Source: https://ell.stackexchange.com/a/564/6697).

This sentence does not seem to contain any 'negative context/comparatives'.

So foolish, unreasonable, or out of place as to be amusing.

(Source: the definition of 'ludicrous' on Oxford Dictionaries).

This sentence does not seem to contain any 'negative context/comparatives' either.

And this post was not meant to be derogative in any way... I am sorry if anyone got offended.

I have also left the exact URLs of most of the websites I have linked to (without having used the hyperlink function) so as to let the users see some information about the links given before having them clicked on the link.

(additionally, is 'before having them clicked on the link' grammatical? I am not a native English speaker and I'm trying to get a hang of some more advanced kind of structures).

Some justifications of the uses of 'so...as...' in the two given sentences would be appreciated (as well as some other grammar corrections present in this post, if possible). Thanks!

  • As StonyB mentioned, "so ... as is not accepted in affirmative comparatives. This has nothing to do with the construction so as to VERB, which is an adverbial of purpose." Jun 25, 2014 at 17:04
  • @DamkerngT. This is not exactly 'so as to', though. This is 'so ... as to', which has created the confusion in me. This is clear now. However, this does not explain the usage of 'so long as', which, as I understand from CocoPop, is something that has to be remembered and is an exception to the rule of the use of 'so...as...' in comparisons.
    – user26486
    Jun 25, 2014 at 17:14
  • @DamkerngT. But wait a minute... I can't really see any purpose expressed in 'So foolish, unreasonable, or out of place as to be amusing.'. And 'so as to' in itself does express purpose.
    – user26486
    Jun 25, 2014 at 17:18
  • So as to ... and so ... as to ... are of different structures. You seem to be aware of the difference already. I think I'd better leave the case of so long as (clause) for others to explain it. Jun 25, 2014 at 17:24
  • So long as I'm here (okay, I know that's stretching the usage a bit), I may as well point out that so far as I'm concerned, "so long as" isn't really an "exception" in the sense of being a "one-off" usage. It's one of many constructions where so can be replaced by as. Jun 25, 2014 at 17:30

2 Answers 2


The posts you link to speak of the use of so ... as ... and as ... as ... in comparisons. In that context the “rule” is as stated: so is employed only in negative comparisons.

But in the two counterexamples you cite, there is no comparison. It is not asserted that the measure of one quantity or degree is less than, greater than or equal to the measure of another. Rather

  • In the first, the so... as ... construction is used not relatively but absolutely, to introduce a measure of the extent to which the preceding assertion is true. There is only one measure, not two.

    While expressions of this sort undoubtedly have the same origin as the comparative construction, the difference between the two uses is so marked that they are no longer apprehended as the same. In the early 20th century so was deprecated in this use, but it has always alternated freely with as in ordinary speech, and today it is generally permitted again.

  • In the second the construction is not so ... as ... but so ... as to VERB, with the same sense as so ... that it VERBs: “so foolish ... that it is amusing”. Again, this is not a comparison of two measures but a single measure.

  • Spot on; the O.P. has fallen into the trap of trying to make a "rule" more universal than it is. This reminds of the debate that sometimes rages over the spelling mnemonic "i before e, except after c." Some argue that it's not a good rule, because there are plenty of words where the rule doesn't hold (such as foreign). However, the rule is meant to apply only when the ei or ie pair make the long i sound, such as in deceive or thief. We need to be especially careful about scoping such "rules" when the rules use those little, versatile English words, like to, so, and as.
    – J.R.
    Jun 26, 2014 at 8:56
  • Thanks, your explanation sounds logical. However, what do you think about Ian Leith's answer? He has provided some rules I have never heard about and haven't seen you write about. The sentences 'John is not so tall as Jeff.', 'Sara does not play so well as Tine.' and 'This beach does not have so much sand as that beach.' look alright to me, since they go according to your rule - whenever there is a comparison of two measures in negative context, 'so...as...' can be used. But Ian Leith claims the three sentences presented are illegitimate.
    – user26486
    Jun 26, 2014 at 11:33
  • @mathh As I explain at the question you linked, the 'negative so ... as "rule"' was never observed much outside of formal writing. Ian Leith's answer describes most conversational use, and the only reason I do not upvote it is because he specifically excludes so with negative comparisons, which I think goes too far. Jun 26, 2014 at 11:39

There are cases where only one should be used, and cases where they could both be used.

Only use "as ... as" when comparing more than thing.

  • John is as tall as Jeff
  • John is not as tall as Jeff
  • Sara plays as well as Tina
  • Sara does not play as well as Tine
  • This beach does not have as much sand as that beach.

It would be strange to use "so...as" in these sentences.

Only use "So ... as" when adding a quality to a single thing. Only use "So...as" if you can rewrite the sentence with "To the degree that."

  • So Foolish, unreasonable, or out of place as to be amusing. Foolish, unreasonable, or out of place to the degree that it is amusing
  • So difficult as to be impossible. Difficult to the degree that it is impossible.

The cases where both can be used interchangeably include when the phrase can be rewritten with "If:"

  • Like the coordinating conjunctions, it is perfectly fine to begin sentences with because, if you keep in mind that the goal is to avoid fragments.
  • I am still wondering why all the other posters, including @StoneyB, haven't added anything about the rule 'Only use "as ... as" when comparing more than thing.', if it is correct.
    – user26486
    Jun 25, 2014 at 18:49
  • Could you add some reference to the 'Only use "as ... as" when comparing more than thing.' rule? I am not sure whether it is something you have created yourself just because it sounds logical or it is a confirmed grammar rule. I cannot find this rule anywhere on the Internet, but I am not a reliable search engine and I can't confirm it is not there somewhere.
    – user26486
    Jun 25, 2014 at 19:20

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