Correct usage of "aber" and "sondern"

Question

In a recent press article, the Austrian Health minister is quoted talking about the trend in Corona cases:

"Es ist kein exponentieller Anstieg, aber ein linearer", sagte der Gesundheitsminister.

The rule that I have used so far is that aber can only appear after a negation if the two pieces of information can occur at the same time, otherwise sondern has to be used. E.g.

Hannah ist nicht arm, aber demütig. (being poor can exist at the same time as being humble)

Hannah ist nicht arm, sondern wohlhabend. (being poor is mutually exclusive with being wealthy)

There is a Stack exchange post that discusses the use of aber vs sondern which seems to align with this rule.

Assuming that something cannot grow exponentially and linearly at the same time, then the ministerial statement should have used sondern rather than aber.

Do I need to change my usage rules for aber?

Answer 1

I don't know what the exact context around that sentence was, I think in this case it's relevant to know what he wanted to express.

You're right, usually you would say sondern in this case, for "correcting" the word used before (exponential). However, it might be that he wanted to stress that there is an increase, not exponential, but still linear. In this case, the sentence would mean the same as "Es ist (zwar) kein exponentieller Anstieg, aber (dennoch) ein linearer", and the use of aber would be correct.

Answer 2

The explanation that you are giving for the difference between "aber" and "sondern" sounds very good to me as a native German speaker. What I can add is:

• „nicht [a], sondern [b]”: means [a] is not the case, but [b] is the case. Contrary to [a]. (a sidenote: as a German speaker I find it weird somehow when other languages use the word meaning "aber" here). Other words in English may be "instead" or "rather".
• „nicht [a], aber [b]”: this is basically the word "but" in all its more complicated or nuanced meanings: to express reservation, to correct, to add additional information or something that is against the listeners' expectation. So it means [a] may not be the case, but still [b] is the case. Or: Just because [a] is the case, it doesn't mean [b] isn't the case. English synonyms could be "yet", "nevertheless", or "but still".

If I had to translate the English sentence "It's not an exponential increase, but a linear one" into German, I would surely translate it with "sondern": "Es ist kein exponentieller Anstieg, sondern ein linearer". This would emphasize that the grow is linear = not a big increase. In the context of the Corona pandemic, that would imply that he would mean we do not need to take stricter measures, because the increase is not so bad.

As far as I understand him, the reason why the Austrian Health minister used the word "aber" here is to emphasize that there is an increase: "It's not an exponential increase. But still, it is an increase". This emphasizes not the adjective, but the noun ("increase"). In the context, this implies that he means we must take stricter measures, because an increase is still there.

Stylistically, it would have been good if he had added the word zwar: Es ist zwar kein exponentieller Anstieg, aber ein linearer.

sondern: https://www.duden.de/rechtschreibung/sondern_jedoch_hingegen, aber: https://www.duden.de/rechtschreibung/aber_Konjunktion_Bedeutung_doch