I’m puzzling through some of the nit-pickier minutiae of grammar intertwined with vocab. So, I’m looking for a little help untangling my thinking/understanding.
Here’s my current tangle (definitions pulled from Jisho/JMdict by using 10ten Reader browser plugin):
そうだ
(1) (int) that is so; that is right; it looks to me; that’s my impression
(2) (exp) people say that; it is said that; I hear that (after plain form of a verb or adjective)
What is the ‘opposite’ or perhaps ‘negation’ of そうだ, meaning “that is so”?
The First Way
(aka longer but maybe more logical?)
Here’s one way of thinking about it…
Please expand for full train of 'grammatical reasoning'
だ is the plain copula:
だ
(1) (cop) be; is (plain copula)
(2) (aux-v) did; (have) done (た after certain verb forms; indicates past or completed action)
(3) (aux-v) please; do (indicates light imperative)
The main idea here is to ‘negate’ だ. However, that is not necessarily so straightforward – this is, after all, an essential aspect of the main question of this post.
Luckily, we can go a slightly different route which has a more well-defined ‘negation’. The ‘formal’ coupla is である, which has the same definition as だ (acting as the plain copula):
である
(cop,v5r-i) (form) be; is
So, if we can figure out the ‘negation’ of である, then we can likewise figure out the ‘negation’ of だ – since definitionally, である ≡ だ, so it should follow that, definitionally, neg(である) ≡ neg(だ).
The ‘negation’ of である is given straightforwardly by でない. (It even says so in the definition!)
でない (exp,adj-i) is not; am not; are not (negation of である)
It seems to me that this makes sense if and because である = で + ある, where で is:
で, にて
(1) (prt) at; in (indicates location of action; にて is the formal literary form)
(2) (prt) at; when (indicates time of action)
(3) (prt) by; with (indicates means of action)
(4) (conj) and then; so
(5) (aux) and; then (indicates continuing action; alternative form of 〜て used for some verb types)
(6) (prt) (ksb:) let me tell you; don’t you know (at sentence-end; indicates certainty, emphasis, etc.)
and ある is:
有る, 在る [ある]
(1) (v5r-i,vi) (uk) to be; to exist; to live (usu. of inanimate objects)
(2) (v5r-i,vi) (uk) to have
(3) (v5r-i,vi) (uk) to be located
(4) (v5r-i,vi) (uk) to be equipped with
(5) (v5r-i,vi) (uk) to happen; to come about
And because the negation of ある is the special case, ない:
無い [ない]
(1) (adj-i) (uk) nonexistent; not being (there)
(2) (adj-i) unowned; not had; unpossessed
(3) (adj-i) unique
(4) (adj-i) not; impossible; won’t happen (as …ことがない, etc.; indicates negation, inexperience, unnecessariness or impossibility)
(5) (adj-i,aux-adj) not (after the ren’yōkei form of an adjective)
(6) (adj-i,aux-adj) to not be; to have not (after the -te form of a verb)
So, the ‘lesson’ I’m taking from here, so far, is that:
IF
- でない (= で+ない) is the ‘negation’ of である (= で+ある)
because - ない is the ‘negation’ of ある
THEN
- if we can figure out what で+ない means, we will thus have the answer to ‘what is the negation of the copula?’
And since ‘the copula’ means the same thing whether it’s である or だ, then
neg(である) ≡ (で + ない) ≡ neg(だ).
So, all that remains is to figure out what で + ない means.
And this involves figuring out which definitions of で and ない to use from the above-given definitions.
For で, it is either (4) or (5). To refresh our memories, they are:
(4) (conj) and then; so
(5) (aux) and; then (indicates continuing action; alternative form of 〜て used for some verb types)
My hunch/assumption is that it is kind of a combination of both of them. In particular, I think the で in this case is the 〜て form of だ (def’n 5) which also happens to be the conjunctive で (def’n 4), because you get the conjunctive form of a verb (or in this case, a copula) by putting it in 〜て form.
So, if my hunch is correct, then で = Te-form(だ).
Next, we must figure out which of these definitions of ない is the one being used here? It seems to me that only (1) and (6) might make sense; the others are ruled out for various reasons of grammar, e.g. (5) doesn’t make sense because in でない, the ない is definitely not following ‘the ren’yōkei form of an adjective’, since the で is not an adjective. For refresher:
(1) (adj-i) (uk) nonexistent; not being (there)
(6) (adj-i,aux-adj) to not be; to have not (after the -te form of a verb)
Well, if で = Te-form(だ), then it looks like (6) is probably the most correct one. [Let me know if I’m wrong here and (1) actually is the correct one.]
So then, ない = to not be, or, to have not.
So then, で + ない = Te-form(だ) + ‘to not be’.
And, lo and behold, this does comport with the previously-mentioned definition of でない:
でない (exp,adj-i) is not; am not; are not (negation of である)
But now we have a tiny little bit more detail and structure to it. Specifically, we know that it’s not just a single word spelled ‘でない’, it’s actually Te-form(だ), followed by ‘to not be’.
And so, bringing it all together, we can answer the original question:
The ‘opposite’ (or ‘negation’) of そうだ is obtained by negating だ, which is the same as negating である, and this negation is でない which we can now interpret with a bit more detail as で + ない, which is really Te-form(だ) + ‘to not be’.
So, the opposite of そうだ = そうでない, which, if I’m correct, should mean something like
そうで + ない = Te-form(そうだ) + ‘to not be’
~= (the statement that “that is so”) is not.
~= “that is not so”
So, if this is correct, then the ‘opposite’ of そうだ is そうでない, and it means “that is not so”.
Checking in with our definitions, we find this entry:
そうでない (exp) not so
Seems pretty close!
But I’m not 100% sure. Because…
The Second Way
(aka shorter but maybe the wrong idea?)
One of the first rules we learn in grammar is that the ‘negation’ of (A)だ is (A)ではない or, equivalently, in terms of definitions, (A)じゃない.
Therefore, the ‘opposite’ of そうだ, by this rule, should be そうではない.
Now, unfortunately, そうではない does not appear directly in Jisho/JMdict, so we can’t just pull up a definition (using this dictionary anyway).
Instead, we’ll have to try something like Google Translate (same result with or without terminating 「。」):
「そうではない。」, 「そうではない」
it’s not; it is not; that is not the case
or DeepL (result depends on if it’s a sentence fragment or terminated full sentence):
「そうではない。」
not so; it is not
「そうではない」
no, it isn’t; it isn’t; not exactly; no, it is not
So, I’m not 100% sure what to make of this either. We get a more complete thing like ‘it is not’, but in some cases we also get the same fragmentary result that the Jisho def’n gave for そうでない, like ‘not so’.
As a final sanity check, let’s see what GT and DeepL make of そうでない. First GT:
「そうでない。」, 「そうでない」
not so; that’s not the case
(both get ‘re-translated’ as そうではありません, which is weird; why switch to polite?)
DeepL:
そうでない。
not so; not really; it is not
そうでない
not so; not likely to (do); not really
Trying to help with using the (rare) kanji version, 然う, doesn’t work, as GT misreads it as ‘shika u denai’, and DeepL misreads it as ‘zen u denai’
The question remains, and new questions remain
What is the ‘opposite’ (or perhaps ‘negation’) of そうだ ? Just, like, in general?
But also: Is そうでない correct? Is そうではない correct? Are both correct? What’s really the difference between the two, anyway? What’s the ‘grammatical reasoning’ that makes sense of this? What’s the ‘closest’ English translation?
In particular: Did you find any problems in my line of ‘grammatical reasoning’? Please let me know if so. This is the kind of nit-picky minutiae I’m trying to wrap my head around – and there’s a deeper purpose to this exercise, as it’s a prelude to another problem I’m trying to figure out, which may have some actual relevance to some of BP’s Vocabs and perhaps even some of their Grammar points.
And also: Is ‘opposite’ the right word? ‘Negation’? Is there a more-correct term for this question?
Are there different kinds of ‘opposites’ of sentences/phrases? Like, you could ‘negate’ the English “That is so.” in ‘different’ ways, like “That is not so.” or “It is not the case that ‘That is so’.” or maybe “‘The opposite of that’ is the case.” or whatever!
Any thoughts, commentary, direct answers, whatever you can think of, would be appreciated! 
