Pappus' Collection, Book III: doubting a standard translation of one sentence
I'm trying to understand the opening philosophical/methodological remarks in Book III of the Collection of the geometer Pappus of Alexandria, and I suspect that the concluding sentence of these remarks could have been misunderstood in standard translations. It reads:
ἑὰν δὲ προσποιούμενος ᾗ τὰ μαθήματά πως ἀπείρως προβάλλων, οὐκ ἔστιν αἰτίας ἔξω.
Taking into account context and grammar, I suspect that this translates roughly as
"If however one somehow ineptly puts forward something claimed as a piece of knowledge, he is not without blame."
This is very different from three published translations of these opening remarks that I'm aware of, and they nearly agree with each other on this sentence. For example, the latest one reads
"But should he, at the same time, pretend to know something in mathematics and so to speak cast forward something in an inexperienced way, he is not without blame"
Now I don't see where in the Greek text they find anything like "to know" and "and"; conversely, nothing in their translations seems to correspond to the word ᾗ. If ᾗ were a verb (from εἰμί or ἵημι), then wouldn't it be in the infinitive? In any case, εἰμί and ἵημι don't seem to admit the meaning of "know".
Here is the full passage:
The translation above quoted is from
p.119 in A. Bernard, Sophistic Aspects of Pappus's Collection, Archive for History of Exact Sciences 57 (2003), 93-150
The other two translations are in
p.566 in Volume 2 of I. Thomas, Selections Illustrating the History of Greek Mathematics, Harvard Univ. Press, 1939;
p.170 in S. Cuomo, Pappus of Alexandria and the Mathematics of Late Antiquity, Cambridge University Press, 2000.
I would be very grateful if someone could either confirm my reading (or suggest a better one) or explain why Bernard, Thomas and Cuomo translated it the way they did. Thank you.