If all of Halacha was Given at Mt. Sinai,

Talmud: 2 points:

1: Not all Halacha was given at Sinai (wait before you call me a Kofer). New cases which did not exist come up, and being a Posek Halacha is working the process of how to pasken and where to place the question. A perfect example of this is the “Shabbos Mode” ovens which the Star-K allows to be adjusted on Yom Tov.

2: Already at the time of Yehoshua, many Halachos were forgotten. You have to remember that the TSBP was transmitted orally, which is ripe for breeding mistakes. Many times in the Gemorah we have two talmidim who say the exact opposite B’shem their Rebbe, while their Rebbe only held one opinion.

Talmud: The Geonim assume that because we were persecuted and because Beis Hillel and Beis Shammai couldn’t properly learn everything, we lost our Mesorah and disputes arose as to what the Halachah that was given at Sinai was. The Rambam has a drastically, drastically different Shittah on this.

Gavra,

The principles behind the halachos were given, so point 1 still requires point 2.

DY: It is a question of application, which may differ Al Pi Svorah.

(You might want to read the Tzvi Lampel’s translation of the Rambam’s introduction to Pirush HaMishnayos, and his books the Dynamics of Dispute). But in short the answer is as follows:

When we say that Torah Shel Bal Peh was given from Hashem to Moshe we mean different things depending on the subject. So there are some halachos that are Moshe m’pi HaGevurah as it is understood simply (e.g. the color and shape of teffilin). There are other parts of the Oral Tradition that are received understandings/interpretations as to the meaning of words in the Written Torah (e.g. that “an eye for an eye” refers to a monetary payment). In these areas there can be no dispute in principle (one cannot argue on what Hashem told Moshe) but only a dispute as to what the tradition actually is. Therefore dispute in these areas arises only because somebody forgot or made a mistake in the chain of tradition.

Moshe Rabbeinu was also given a series of methodologies (like keys to a code) that would allow the Chachamim to derive new halachos when faced with new situations. It could also be used to revive forgotten halachos. On these, in each generation a given Sanhedrin could argue and reverse the decisions of a previous Sanhedrin and therefore the Halacha could change. Of course human beings can have machlokes in the applications of these methodologies. While in earlier generations these machlokesim could be resolved by the Sanhedrin, in later generations when there was no regularly sitting Sanhedrin, machlokes could proliferate.

Of course there were also many disputes about whether or not to make gezeiros and takanos, and then later about the extent of those gezeiros, their applicability to new situations, etc.

Which death penalty to give to the Sabbath desecrator

Inheritence when there are daughter(s) but no sons

The gemorah discusses each of these cases, IIRC (Megalgalin). From what I have learned, according to the Shittah of Torah Chasumah Nitna (that we are assuming), the question was one of applicability (meaning if the Halacha as will be tought should be applied at that point), not of knowledge.

That’s very difficult to say when the pasuk explicitly states that the manner of death penalty for the Shabbos desecrator was not explicitly stated.

I’m not sure what you mean by “that”. Would you mind expounding a bit?

The Torah says ” ???????????? ?????, ????????????: ???? ??? ??????, ???-????????? ???.”

The Gemorah explains in BB 119A:

????? ??? ??? ????? ??????? ????? ????? (???? ??) ?????? ??? ???? ??? ?? ??? ???? ??? ?? ???? ??? ????

Assuming Torah Chasumah Nitna, that means Moshe knew the Mikoshsh should get skilah, but was unsure if the din was “ready” to be applied, as Hashem did not yet “officially” tell him.

A similar question would have come up if a bird’s nest was found during the time the Beni Yisroel were in the Midbar. Since the Parsha of Shiluach Haken was not yet officially said, Moshe would not have been able to tell the BY to do the mitzva.

Of course not all of halachah was given at Sinai — the rabbinic decrees were in the future.

I think you left out a point. Not just Nevua and Sanhedrin. The Gemara says Kishenismaatu Liban and Kishelo Shimshu Kal Tzarchan, is when Machlokes began. The Rambam learns that when a Talmid properly understands his Rebbe, his attitude and his take on a situation would be exactly like that of his Rebbe.

Once they weren’t Mekabel fully to this degree their view has a flavor of their own. This breeds Machlokes, since each Talmid has his own view and they are not reflecting the one view they recieved together.

Intro to Peirus Hamishnayos, I think.