More good stuff from Rabbi Zemer's "Evolving Halacha:
"The view of halakhic authority held by Orthodox Judaism is quite different from that maintained by Progressive Jews. This latter term refers here to certain circles of rabbis and scholars affiliated with the Movement for Progressive Judaism (which goes by the names 'Reform,' 'Liberal,' or 'Progressive'), with the Masorti (Conservative) Movement, and with the Reconstructionist Movement, and a number of Modern Orthodox rabbis. Milton Steinberg categorized the outlook of these circles as 'modernist' (a term I shall use frequently below), as opposed to the 'traditionalist' approach of Jews with a fundamentalist philosophy. In fact, this difference is perhaps the major source of contention between Orthodox and non-Orthodox decisors. The Orthodox stance is summarized in a brief submitted by the Chief Rabbinate Council in response to a suit brought by the Israel Movement for Progressive Judaism, asking that its rabbis be granted the status of marriage registrars and the right to officiate at weddings in Israel.
The Rabbinate's brief advanced two main arguments: (1) The Torah given to Moses on Mount Sinai and the rulings of the Sages have absolute authority. (2) Nothing may be changed in Halakhah, whether in response to contemporary circumstances or to the urgings of individual conscience....
Although the Chief Rabbinate offered no textual support for its position that Halakhah is static and immutable because the Revelation on Mount Sinai was a one-time event valid for all generations, there are classical texts that may be interpreted as supporting this view. Citing the verse 'these are the laws, rules, and instructions that the Lord established, through Moses on Mount Sinai, between Himself and the Israelite people' (Lev. 26:46), the Sage remarked that 'this teaches that the Torah--its laws, details, and interpretations---was given through Moses on Sinai' (Sifra, Behukotai 8:12). In the Gemara, Rabbi Simeon ben Lakish holds that not only the Torah--that is, the Pentateuch--but also the Prophets and the Hagiographa, the Mishna and the Gemara, were all given at Mount Sinai (BT Berakhot 5a).
If everything was already revealed at Sinai, there is no room for innovation and change. Indeed, the conclusion inferred from the concept of a perfect revelation at Sinai is that 'no prophet is permitted to innovate in any matter from this time on' (BT Shabbat 104a). If prophets are so restricted, how much the more are rabbis and scholars: 'Even what a long-time student will one day expound before his teacher was already given to Moses at Sinai' (JT Pe'ah 2:4). It is this fundamentalist position that leads most Orthodox thinkers to reject the historical and scientific view of the evolving nature of the Bible and rabbinic literature held by modernist Jewish scholars.
On the other hand, there are also many passages in which the Sages recognized the fact that Judaism changes. Consider the well-known midrash that Moses visited the academy of Rabbi Akiba (early second century) but 'did not understand their discourse [about the Torah he had received] and felt faint.' Only when a student asked Rabbi Akiba for the source of his teaching, and the Sage replied that 'it is a Halakhah given to Moses on Sinai,' did Moses recover (BT Menahot 29b).
For the British Rabbi Louis Jacobs, this midrash could be interpreted as follows:
"The Torah that Akiba was teaching was so different from the Torah given to Moses because the social, economic, political, and religious conditions were so different in Akiba's day that, at first, Moses could not recognize his Torah in the Torah taught by Akiba. But he was reassured when he realized that Akiba's Torah was implicit in his Torah, was, indeed, an attempt to make his Torah relevant to the spiritual needs of Jews in the age of Akiba."
pg. 43 "The constant, dynamic changes in human society make it impossible to record the particulars of all customs and provide an account of all epochs to come. Hence, the Oral Law includes general principles that make it possible for the wise schoalrs of every generation to apply them and interpret the Written Law for their own age. One cannot help contrasting Albo's dynamic approach to the evolution of Halakhah with the position of those who believe that it all began and ended at Sinai."
pg. 43 "...liberal scholarship has reached the conclusion that 'long before the rise of modern criticism some of the Jewish teachers had a conception of revelation which leaves room for the idea of human cooperation with the divine.'
How is the divine will revealed in the Halakhah? According to Jacobs,
'Revelation must be understood as a far more complicated and complex process of divine-human encounter and interaction and quite differently from the idea of direct divine communication of infallible laws and propositions, upon which the traditional theory of Halakhah depends.'
Evolving, modernist Halakhah, then, must be founded on such a reinterpretation of revelation."
pg. 44 "This theological-halakhic position has implications for the authority of traditional Halakhah. For the non-Orthodox Jew:
'The ultimate authority for determining which observances are binding upon the faithful Jew is the historical experience of the people of Israel, since, historically perceived, this is ultimately the sanction of the Halakhah itself.'"