There are many differences between the Jerusalem and Babylonian Talmuds not only in halachah, but also in ideology. This is especially evident in the area of Mesorah. Both Talmuds recognize the immutability of the laws given to Moses, both in writing and orally, as well as the necessity of obeying the enactments of the Sanhedrin, as commanded in Deuteronomy 17:8-13. However, there is a major difference when it comes to the question of Minhag (custom) in relation to law. The entire topic of Minhag is in a brief section in tractate Pesachim, relating to different traditions as to what may or may not be done on the day before Passover. The Babylonian Talmud is very clear. Customs are geographic and not genetic. A custom may enlarge on an existing tradition, but not detract from it. If one moves temporarily to a place with a different custom, one must abide by the stricter of the two practices. If the move is permanent, one jettisons one's former custom, and conforms to that of his new community. If the Babylonian rabbis encountered a custom which they considered mistaken or baseless, they would oppose it. The Jerusalem Talmud, on the other hand, records cases where rabbis visited communities with odd customs, but upheld those customs themselves while visiting these places. The concept was formulated that custom could even trump a law. These issues later became factors in the differences between Ashkenazi and Sepharadic practices. The original Ashkenazi traditions were those of the Jerusalem Talmud.When the ruling was accepted (about the year 900) that the law follows the Babylonian Talmud, many Eretz Israel traditions were nevertheless maintained. Even if they had no basis in statutory law, the fact that these traditions were ancient made them part of the Mesorah. One contemporary Jerusalem posek (legal decisor) wrote a responsum to a question as to why, when dealing with issues of law, he took very lenient stances, while being extremely strict in matters of custom. He answered "when it's a question of law, it's an argument between Rabbi A and Rabbi B. I know how to judge that. When it's a question of custom, I have no idea if it is simply folklore, or an ancient enactment, perhaps going back to Moses! Therefore, I need to be strict!" As new customs came in throughout the ages, the tendency of the Ashkebazi rabbis was to formulate theories as to why they had come about, and sought "hints" in the sources to justify the custom. Sepharadic rabbis, on the other hand, usually fought practices that had no apparent basis. One contemporary Sepharadic posek writes that any custom not mentioned in Talmudic  sources should be assumed to be non-Jewish, and abolished. Maimonides wrote that no custom is universal unless it came into being by the mid fourth century, predating the demise of the last Sanhedrin. Any later customs only have local validity, and none if they contradict the halachah. It was only in the last few centuries, as a result of Jews being uprooted from place to place, did the concept of family custom become widely accepted. This has been rejected by most Sephaardic rabbis. However, most Ashkeanzic and Sephaardic rabbis refrain from openly opposing the other community's customs, seeing peace among the various segments of Jewry as overriding other considerations. Here we have a blurring of the lines between Mesorah, "handed down" Tradition, Custom, and statutory halachah. But some "blurrings" are less founded upon ancients differences of opinions, and more on "extra-halachic" considerations of various kinds. That will be my next post.