I've encountered the phrase datum (sed) non concessum in various English-language books and articles such as:

It's clear that datum and concessum are passive past participles in Latin; datum can mean 'given' and concessum can mean 'conceded' or 'withdrawn' among other possibilities.

So the phrase would seem to mean something like, "if we grant the preceding proposition for the sake of argument, without actually conceding that it's true, ..."

For example,

But allowing for the moment the truth of this hypothesis, datum non concessum, how is this episcopal collegiality supposed to have shown itself?


However, the critical question was ... One might argue that ... All right, datum non concessum the issue still remained as to why ...

And the other links show similar constructions. Is my understanding (which is based on the meanings of the individual words and on context) correct? Can anyone point me to a standard reference that describes the usage of the phrase?

P.S. There is some question as to whether this counts as an English phrase (idiom), or only a Latin one. (Actually I don't have evidence that the phrase is used in Latin, but that's not the main point.)

That's an open question, but in my favor, there are currently 4850 Google results for "datum sed non concessum". Even given that many of these are duplicates and not all are in English, nevertheless a good many of them appear to be unique, English-language pages. Usage does seem to be concentrated in circles of Catholic theology.

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    This question appears to be off-topic because it is about Latin, not English. Educated writers are free to add any non-English expression to their prose, but we are not required to weigh in on such, nor is it appropriate for us to do so.
    – Robusto
    Commented Jan 15, 2015 at 15:18
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    The short answer is that concessum non datum, which can be translated simply as granted, not given, is a rhetorical tool which offers a concession to a premise of the opposition, serving to strengthen the argument later. You may find the Italian formulation dato, non concesso, also meaning to agree for the sake of argument, to be more common. A less pretentious way to say it in English would be granted or given that, or I will stipulate.
    – choster
    Commented Jan 15, 2015 at 15:38
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    @choster "Given, (but) not granted" or "given, (but) not conceded" surely? But yes, it's used to say "I'm not conceding that point, but if it that point was true then..." before arguing how your general case is correct even if that point was true.
    – Jon Hanna
    Commented Jan 15, 2015 at 16:50
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    @Robusto: I disagree... It is about Latin, and English. This phrase appears to be used in English just as "sina qua non" or "QED" are. Yes, it's Latin, as are many other English phrases. If you assert that the phrase is not well-known enough in English communication be counted as on-topic, please cite your data to support that assertion. I'll add mine to the question.
    – LarsH
    Commented Jan 15, 2015 at 17:38
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    @Robusto: I included a cursory analysis of the Latin meaning of the phrase, as relevant background information, but my question is not about the Latin meaning. It's about the English meaning. Regarding your second sentence, can you be explicit about how objective measures of occurrence of datum (sed) non concessum establish that it is not an English phrase?
    – LarsH
    Commented Jan 15, 2015 at 18:22


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