The idiom "Ausnahmen bestätigen die Regel" exists in English, too.

The exception proves the rule.

However, someone recently told me that this originally was based on the old meaning of "to prove", which is still conserved in German "prüfen". So the original idea was

The exception tests the rule.

Which makes a lot of sense. I was then trying to find out whether the German version is just a flawed translation but all I could find were somewhat philosophical treatments on why it makes sense the way it is. So here's my question:

  • Where does the idiom come from?

1 Answer 1


The phrase is, in essence, correct - it's not "tests" but "proves", because the idea is that if I say "well that's an excpetion", then this means that there must be an underlying rule of which the exception is an exception. This is a Roman legal principle, so the whole saying is derived from Latin:

exceptio probat regulam in casibus non exceptis

which translates to "the exception confirms the rule in cases not excepted". This then gives you the meaning as above - however we (in German or English) tend to not use the second part of the phrase.

So far Wikipedia knowldege. Now, what's odd is that the real source of this (which is supposedly Cicero's "Pro Balbo") does not pop up (on the first google page) when you search for the above Latin phrase. Digging a bit deeper, this is what I found:

Quod si exceptio facit ne liceat, ubi necesse est licere.

in Cicero, Pro Balbo, Caput XII,

which translates to "If the exception makes such an action unlawful, where there is no exception the action must necessarily be lawful." - i.e. a twisted wording of the above (translation not by me).

Another version is

Exceptio firmat regulam in casibus non exceptis

the only difference being that "probare" (prove) is exchanged by "firmare" (confirm, strengthen). Now having a look at this phrase, you get more lucky. This was discussed in normal Roman law throughout the ages, see e.g. here or here.

In conclusio: Above, you find the original phrase used by Cicero. The other versions (exceptio propat/firmat regulam in casibus non exceptis) are derived from there, but were around since Cicero and they mean what Cicero meant and what is more aptly be translated as "Ausnahmen bestätigen die Regel" or "exceptions prove the rule".

  • But "probare" also means "to test" (dela.dict.cc/?s=probare or de.pons.com/%C3%BCbersetzung/latein-deutsch/probare), so this explanation is nice, but leaves the question still unanswered... Commented Apr 2, 2014 at 7:54
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    @ThorstenDittmar This is only true if you ignore a) the latter half of the sentence ("in casibus non exceptis") and b) the last third of Martin's answer ("Exceptio FIRMAT...").
    – elena
    Commented Apr 2, 2014 at 8:41
  • "probare" means "to test" no matter whether a) or b). Of course the sentence changes its meaning if you change the verb! The original question is, however, why can you derive the English version from "The exception tests the rule" while the German version can not be derived from "Die Ausnahme prüft die Regel". Commented Apr 3, 2014 at 7:30

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