French has "si" from "sic" as well! Used in an affirmative response to a negative question. Pulling an example from wiktionary:

    Tu ne m’aimes pas, n’est-ce pas ? — Si !

    You don’t like me, do you? — Yes, I do!

This has interesting consequences on my speaking English.

    Do you not like me?

In French this question including a negative would invite two responses, either "no" (negative agreement, I don't like you) or "si" (positive disagreement, I do like you). No French person would reply "yes" to such a question (that would be ambiguous) or be confused by the "no" or "si" answers.

Of course there is no "si" in English and I know that, but because I grew up speaking French, I intuitively understand "no" to mean agreement, which is not usually what a native English speaker means. I will also tend to reply "no" to mean agreement, though I will not reply "yes": I will notice that I can't say "si", but forget that the absence of "si" also means I can't say "no".

English used to have this distinction, we used to use "yes" as a strong affirmative, and "yeah" otherwise. We still use both words but the distinction between them has disappeared.

I'm curious if you or someone else can answer this: is this use similar or identical to the German "doch"?

I've always like "doch", which was explained to me as meaning "I agree with you", and spares the speaker the effort of matching the negatives or not in the question.

"Are you going to the club then?" "yes" "doch" "Are you not going to the club then?" "no" "doch"

That's not how "doch" works. It's the German "though" and works to mean effectively "on the contrary" in response to a negative question. It doesn't work in response to a positive question.

"Du magst mich nicht?" You don't like me? "Doch" Yes I do.

Ah, that's too bad, although it fits the 'spirit of German' (Deutchgeist?) better than what I misunderstood it to mean.

So yes, the same as the French «Sí» as others have explained it.

> (Deutchgeist?)

Correct spelling would be "Deutschgeist", but it's not a word that evokes much sense. I think a good translation would be "im Geiste der deutschen Sprache", which more literally translates to "in the spirit of the German language". Yeah, sadly we can't use combined nouns for everything...

No, "si" is only used as a positive response to a negative question.

A: Tu ne vas pas au club, n'est-ce pas? //You're not going to the club, right?

B: Si! //Yes! ; this means B is going to the club

B: Oui! //Yes! ; this means B is agreeing with A, indeed B is not going to the club; in practice this is probably somewhat ambiguous

B: Non! //No! ; probably this also means that B is not going to the club, though it could also mean that B is contradicting A: B is going to the club.

In contrast, if A had asked "Tu vas au club?" (Are you going to the club?), B wouldn't normally answer "Si", since "Si" only makes sense as a response for a negative question.

> No, "si" is only used as a positive response to a negative question.

Yes it is/doch/si! :) Because OP misunderstood, "doch" is used exactly the same way as the french "si" and as you described.

It's more about resolving the ambiguity of a negative question. Taking GP's example:

  You don’t like me, do you?

If you just answer "yes", it's unclear if you mean "logical yes" = "It's true, I don't like you" or "semantical yes" = "Why would you say that, I do like you".

French resolves that ambiguity with "si" to mean the latter. In languages like English that don't have the same concept, you would repeat a bit of the question to clarify.

I would generally expect to interpret a "yes" as the former? The "why would you say that, I do like you" seems more like a "no", though troublingly an unqualified "no" probably also implies "No, I don't [like you]." Maybe if spoken with a tone of offense an indignation...

English used to have this distinction using the words "yeah" and "yes" but the distinction in usage has disappeared.

I was going to say that I was fairly sure Latin didn't have "yes", but I was a C student scraping by on the peripheral historical content rather than the language.

Other circumlocutions that I don't think made it into any Romance languages:

"ita" ('it is so', 'indeed')

"ita vero" ('it is so, truly')

"maxime" ('entirely')

"valde" ('very much (so)')

"vere" ('truly')

There are great circumlocutions for "no". I remember Nancy Llewellyn had a whole list, including "haud quaquam" ('hardly/scarcely to any degree'), "nullo modo" and "nullo pacto" ('in no way'), and "nullactenus" ('to no extent'). Latin students are most often taught "minime" ('minimally', 'scarcely').

Without the circumlocutions I think you would simply do what so many other languages described here do, which is repeat the main verb of a question, either negated or not negated.

Nec/necque are a good way to negate in Latin.

In the 11th Century, Peter Abelard wrote a famous book called “Sic et Non” - which is always translated as “Yes and No.”

Even in Classical Latin “ita” was pretty close to yes.

I think an ancient Roman would understand and possibly use sic and ita much as we use “yes”.

But it’s been a while. My Latin is rusty.