In the course of the paper he writes the following: "In the sciences it is fairly easy to date inventions. In the humanities, however, it is rare to be able to date the birth of an idea or a concept." With that in mind, he tries to develop the thesis regarding Saul Ascher's book, which of course dates the concept of Jewish Orthodoxy to the late 18th century generally, but he also shows what the earlier literature had to say about the genesis of the term.
Below are some quotes:
pg. 28-29 section III. THE INVENTION OF JEWISH ORTHODOXY
"What is striking about the words “orthodox” and “orthodoxy” is the fact that they were originally Christian terms. Before the end of the eighteenth century, they had never been applied to Jews."
"The hebraist and theologian Johann David Michaelis, as Mordechai Breuer has shown,17 probably was the first person to attribute the term “orthodox” to a Jew. He called Moses Mendelssohn an “orthodox Jew” in the Göttingische Gelehrten Anzeigen in 1770 following the so-called Lavater affair.18 Another example of a Protestant speaking of the “orthodoxy of the Jewish superstition” is found in an antijudaic reference to the Emden-Eybeschütz affair in an anonymous letter in the second volume of Dohm’sUeber die bürgerliche Verbesserung der Juden (1783).19 Ascher refers to this book, and he mayalso have known that Mendelssohn was the first Jew to publicly use the term “orthodoxJew”, when he wrote that Spinoza (!) could have remained an orthodox Jew if only he had clung to his philosophical ideas in the Ethics instead of attacking various religious doctrines of Judaism directly in texts like the Tractatus theologico-politicus.20
17 Mordechai Breuer, ‘Das Bild der Aufklärung bei der deutsch-jüdischen Orthodoxie’, in Karlfried Gründer and Nathan Rotenstreich (eds.), Aufklärung und Haskala in jüdischer und nichtjüdischer Sicht, Wolfenbütteler Studien zur Aufklärung 14, Heidelberg 1990, pp. 131–142. I thank Renate Best for drawing my attention to this article and to Breuer’s findings.
18 Johann David Michaelis, Göttingische Gelehrten Anzeigen, vol. 1, 59. Stück, 17 May 1770, p. 514.
19 Christian Wilhelm von Dohm, Ueber die bürgerliche Verbesserung der Juden, Zweyter Theil, Berlin and Stettin 1783, p. 131. The letter is signed Gr. v. S. (?).
20 Moses Mendelssohn, ‘An die Freunde Lessings’, Berlin 1786, in Mendelssohn, Gesammelte Schriften. Jubiläumsausgabe, vol. 3.2, ed. by Leo Strauss, Stuttgart 1974, p. 188. In two private letters to Herz Homberg, dated 14 June 1783 and 1 March 1784, Mendelssohn again speaks of Jewish orthodoxy; cf. Mendelssohn, Gesammelte Schriften, vol. 13, ed. by Alexander Altmann, Stuttgart 1977, pp. 112 f. and p. 178.
"Another text Ascher may have known is Moses Hirschel’s Kampf der jüdische Hierarchie mit der Vernunft (1788), in which Hirschel attacked “the orthodox” Jews and the “jüdische Orthodoxie” in a Voltairian manner as representatives of superstition, ignorance, and priestly hypocrisy.21 But in Hirschel’s publication – in contrast to Ascher’s work – there is no proposal for religious change. His anti-religious polemics favour the radical abandonment of the rabbinic tradition without replacing it with any religious alternative."
"Ascher, then, was not the first Jew to write publicly about Jews being “orthodox”– as far as we know Moses Mendelssohn was. But Mendelssohn’s words about Jewish orthodoxy were incidental and not conceptual. Ascher, on the other hand . . . "However,
1761 -- this one is actually Michaelis, who is credited above with calling Mendelssohn an Orthodox Jew in 1770:
Although it is true that many of these are really speaking about Jews in the time of Jesus I think it must be admitted that the suggestion that "before the end of the eighteenth century, [the term orthodox] had never been applied to Jews," as "orthodoxy" is a "Christian term," must be rejected as inaccurate. And it isn't as if I've read through all of early 18th century literature, and these examples are only from English texts. I'll bet the same can be shown in Latin, German, Dutch, Italian, etc.
Secondly, clearly Mendelssohn was not the first to write publicly about Jews being orthodox.
That said, I'll grant that Michaelis may well be the first to speak of a specific Jew as orthodox, in this case, Mendelssohn in 1770, although I suspect that really he is but the first so far noticed.
See also the 2007 article in Modern Judaism "So-Called Orthodoxy": The History of an Unwanted Label" by Jeffrey C. Blutinger who also discusses the history of the attempt to date the origin of the term.
He writes that for a long time it was thought that the published transactions of the Parisian Sanhedrin (1806) were the first use of the term (although I think he meant first published). Below is the reference from the 1807 English translation, the Transactions of the Parisian Sanhedrim [sic] or Acts of the Assembly of Israelitish Deputies of France and Italy Convoked at Paris by an Imperial and Royal Decree, dated May 30, 1806:
Blutinger recounts that in 1956 that date was pushed back to 1795, when the term was found in an issue of the Berlin Monatsschrift. Later Blutinger adds his opinion that Mendelssohn seems to have been the first Jew to use the term Orthodox, however he found this in a letter from 1755, which is 15 years earlier than the letter Schulte found the term in. In any event, the article usefully notes that in its original late 18th century use the terms means "Anti- or Un- enlightened." This is how it was used by 18th century Aufklarung (men of the Englightenment) and this is how it was used by those Jews who had used it. Later it took on the connotation of "Anti-Reform." Obviously the examples I have uncovered have nothing to do with the Englightenment. However, we see that term was most certainly used by writers wanting to contrast something with what was supposed to be the standard or normative -- orthodox -- Judaism.