This Shabbos was the tenth cycle of completion of the Rambam in Chabad and both the three chapters a day and a chapter a day made a completion Siyum. Both began their new cycles with Rambam's introduction to Mishne Torah. This provides me an opportunity to discuss a strange statement that the Rambam makes in this introduction as well as an opportunity to adress one of my loves in learning - Yerushalmi. My comments are partially based on the discussion by Heshy Zelcer in his Guide to the Jerusalem Talmud, page 30.
In his introduction Rambam writes that Rabbi Yochanan compiled the Jerusalem Talmud and the land of Israel approximately 300 years after destruction of the Temple which would be in the year 370 CE. Raavad disagrees and points out that the Mishna was completed 120 years after the destruction and that Rabbi Yochanan write Yerishalmi 200 years after the destruction. This leaves a gap of over hundred years.
Kaftor V'Perach suggests that Rambam means a different R Yochanan. This is very difficult because it is universally accepted that the R Yochanan who wrote Yerushalmi is R. Yochanan ben Naphcha, colleague of Resh Lakish, see, for example, Meiri to Sanhedrin 72b.
Chida (Maarechet Sefarim) suggests that 300 is a printing error that resulted from the abbreviation of the letter shin, which stood originally for R. Yochanan's length of life, shmonim( 80 yars), was later misread as 300. From here also came the tradition found in Seder Tannaim v'Amoraim that he lived 300 years.
An interesting suggestion is offered by Y. Y. Greenwald in an article, Did the Editors of Bavli see Yerushalmi, published in New York , Hadar in 1954. He suggests that the Jerusalem Talmud had two editions and each one had a different editor. This explains why the three Bovos in Yerushalmi are so different in style and are much briefer than other mesechtos ( or in the language of Yerushalmi- mechiltos) in Yerushalmi. This would be because thee represent the initial edition. This is also why R. Yose bar Bun and R. Y barZ evida,presenting respectively the fifth and the fourth generation of amoraim are extensively quoted in Yerushalmi. Presumably they were the final editors of the second edition and R. Yochanan wrote the initial "draft".
I might suggest another reason why Rambam assigns the writing of Yerushalmi to R. Yochanan. Whereas R. Yochanan is treated with great deference in Bavli, he is not considered a Tanna. Although Bavli will go to great efforts to avoid rejecting R. Yochanan's statements, occasionally it does. It usually does not say that R. Yochanan is a tanna and can disagree with a tannaitic source. That is not the case in Yerushalmi. Not infrequently, R. Yochanan is viewed as one of the last generation of Tannaim and he routinely disagrees with tannatic sources brought by Yerushalmi. For example, in Bavli Zevachim 32b, the Gemara answers, "Rav is Tanna and he disagrees", but in the same discussion it does not answer so for R. Yochanan. This means that R. Yochanan, unlike Rav, was not a Tanna. Tosafos writes in in Kesuvos 8a: "R. Yochanan was an Amora and he did not consider Rav a Tanna and he (R. Yochanan) argued with him(Rav)". However, in Nazir 65a it says that R. Yochanan was a Tanna. This relates to what is written in Shearis Yosef(35a) and Shalsheles Hakabola, as we discussed above, that R. Yochanan lived 258 or 300 years and outlived R. Ashi. In Bava Basra 28a he appears to have learned directly from R. Ishmael (unless it is R. Yochanan ben Nuri). which is understndable if he really lived for 300 years. Responsa of Darchei Noam(p.70, siman 19) discusses these sources and concludes that Yerushalmi does not hold like Bavli and considers R. Yochanan to be a Tanna. This may be why Rambam assigns the authorship of Yerushalmi to R. Yochanan, to lend it a greater authority, while also admitting in his Introduction that Bavli is the end-all of Mosaic tradition. Yerushalmi to Rambam was equal to Bavli in authority. He even wrote a commentary on it, entitled Hilchos HaYerushalmi. That was not the approach of Tosafot, see B.Berachot 11b, s.v. she-kevar niftar, where Tosafot state in response to a difficulty presented by a Yerushalmi: “And Ri answers that we do not accept this Yerushalmi since our Talmud does not quote it.”
ביאור הגר”א אורח חיים סימן תלו סעיף א ד”ה א”צ לבדוק
“…אבל הרמב”ם דרכו לנטות אחר הירושלמי ברוב מקומות
On the other hand, this may not be correct because Yerushalmi in general never made a strong distinction between Tannaim and Amoraim. For example, just as we find R. Yochanan arguing on Rebbi, in Peah 1:4 we find R. Yehuda Nesiah arguing on Rebbi and R. Yehuda Nesiah was Rebbe's grandson.(See Doros Hrishonim v.5, 40)
Amalgamated image of T-S F17.7 and the new discovery, T-S NS 284.120
* The crossed-out sentence is clearly in Maimonides’ hand, as this comparison with a similar word from T-SF17.7 shows: