Rabbi Moses Hagiz רבי משה חגיז

Born at Jerusalem in 1671 into a well-known family; he was active at Amsterdam, Altona and London, and died about 1750. He held no great office and wrote no famous book — his importance lies elsewhere: he built a working trans-communal machinery for the prosecution of heresy, resting on correspondence, printed pamphlets and coordinated bans issued by several communities at once.

In 1713, with Hakham Tzvi, he pronounced a herem on the crypto-Sabbatean Nehemiah Hayyun, whose Oz le-Elohim expounded a doctrine of three partzufim in the Godhead that his opponents read as a Jewish trinitarianism. The Portuguese ma'amad cleared Hayyun and turned on them both; Hakham Tzvi left, and Hagiz carried on the pamphlet war.

In 1729–30 the letters of Yekutiel Gordon about the Padua maggid reached him, and he alerted the Venetian rabbinate. Out of that grew the five-year Ramchal affair.

Elisheva Carlebach, whose book on him is the standard work, shows the essential thing: in both affairs it was not doctrine that decided but institution. Hagiz was building rabbinic authority across communal boundaries — in a world where each community held itself sovereign. That is why his cases are so ferocious, and why they ended in expulsions rather than verdicts.