At any point in history was "Why cannot…?" used as frequently as "Why can't…?" Is it even grammatically correct to say "Why cannot you do this?" I know it can be rearranged to be "Why can you not do this?," but I always presumed the contraction and the contracted phrase could be used equivalently, without changing the sentence structure. I think this pattern holds true with the other question words (e.g. how, when, etc.); however, I also know it is common to say "Who cannot do this?" In general, are there rules pertaining to the uses of contractions in questions?
Learn English – Is it incorrect to say, “Why cannot….?”
contractionsgrammaticalityquestions
Related Solutions
None of them are grammatical full sentences, if we don't consider "why so" as having a meaning of its own. And we'll do that in a minute, but let's first pretend that it doesn't have one.
Possible full sentences would be:
Why are you so sure?
How are you so sure?
Why is it that you are so sure?
How is it that you are so sure?
The forms you all have are eliding part of these sentences.
Now, those that do not contain so could be construed as elisions from different questions; asking why someone is sure of something is different to to asking why they are sure to the extent that they are. Of course, we could be asking that, but that's not the form that has become idiomatic, as we'll come to.
The way elision works with contexts is complicated, in that we can understand e.g. some headlines fine that we'd trip up on in the middle of a passage of prose.
And similarly, while "how so sure?" doesn't scan right, we still understand it, and it would unusual, but not utterly bizarre, for someone to use it in informal speech.
Likewise with "why so sure?" except that "why so" has been used so much as to become an idiom of its own, indeed one that is defined in its own right in at least one dictionary.
And so, after that little journey through elision, we can see that because "why so" has been so often used as to become an idiom, we can actually understand "why so sure" without reference to elision at all, but in terms of that idiomatic meaning.
("Why so" was once also used as an expression of relief or acquiescence, as it is used by Shakespeare and continued to be used into the 19th Century, this other meaning might or might not have helped "why so" in the sense here come into being).
"How so" has had a different journey toward becoming an idiom, in that it is often found as the entirety of a question ("How so?"). As such, just as we can understand "why so X?" as an idiomatic form with a defined meaning, so we can "how so?", but not "why so?" or "how so X?" because that is not what those idioms mean.
Its usage is certainly literary and archaic. NGram: curiously shows that its usage peaked in the 18th century, and decreased steadily since then. Unluckily, Ngran does not offer instances of usage earlier than the 16th century.
'TIS: (from M-W)
it is, ( contraction).
Origin - First Known Use: 15th century
'TIS ( from Wiktionary)
(literary or archaic, also occasionally colloquial) It is.
’Tis the season to be jolly. — Popular Christmas song (Deck the Halls).
’Tis good ta’ ’ave ya back boy! (to have you)
1597, William Shakespeare, Romeo and Juliet, Act 3, Scene 1: Mercutio [wounded]: "No, 'tis not so deep as a well, nor so wide as a church-door; but 'tis enough, 'twill serve: ask for me to-morrow, and you shall find me a grave man."
1844, Charles Dickens, The Chimes, Chapter III: It looks well in a picter, I've heerd say; but there an't weather in picters, and maybe 'tis fitter for that, than for a place to live in.
Ngram 'tis, 'twere, 'twas.
Literary quotations with 'tis:
George Eliot:
- “'Tis God gives skill, but not without men's hand: He could not make Antonio Stradivarius's violins without Antonio.”
William Shakespeare:
- “If it were done when 'tis done, then t'were well it were done quickly.”
George Washington:
- “'Tis our true policy to steer clear of permanent alliances with any portion of the foreign world.”
Robert Browning:
- “'Tis not what man does which exalts him, but what man Would do!”
Emily Dickinson:
- “Anger as soon as fed is dead; 'Tis starving makes it fat.”
Best Answer
The transition point was about a century ago
Note that if we substitute a pronoun (I, he, they) for "why", the transition point comes much later (1980 for "I") – or hasn't even happened yet (all other pronouns). I can't explain why that is, except by pointing out that this very sentence is an increasingly typical usage. Maybe we all tend to be a bit less formal when introducing our own selves into the text.
It's only my opinion, but I think can't (similarly, let's) are examples of grammaticalisation. The contracted form has effectively taken on a "life of its own", leading to a situation where OP is prepared to accept that there may be contexts where can't is "grammatical", but "cannot" (or the equivalent "can not") wouldn't be valid.
Using cannot / can not might be a bit stilted in many contexts now we're so used to seeing the contracted form, but I don't think it's ever ungrammatical.