The central authority for determining all issues of halacha is the Sanhedrin that sat in the Beis Hamikdash, and in Parshas Shoftim we are instructed not to deviate from their decisions. There is a fundamental dispute between the Rambam and the Ramban as to the parameters of the mitzva to listen to the words of the Sanhedrin. The Rambam divides halacha into three categories, the first of which is the portion of halacha that was transmitted orally by Hashem to Moshe and subsequently from generation to generation. If a question arises within this area of halacha, the final authority is the Sanhedrin, and one who refuses to follow the tradition of the Sanhedrin in this realm violates the positive and negative commandments which mandate listening to the Sanhedrin. A second category of halacha that the Sanhedrin also has the ultimate authority to decide is application of middos she'haTorah nidreshes bohein. Hashem taught Moshe how to extrapolate new applications of halacha using the rules of interpretation that were transmitted to him. Different opinions that would emerge as to how to apply these rules would be subject to the majority view of the Sanhedrin. The third category of halacha, which the Rambam also subsumes under the authority of the Sanhedrin, is questioned by the Ramban. Throughout history Chazal instituted new halachos known as dinim d'Rabanan. Laws such as lighting Chanuka candles and refraining from not moving muktza were added by Chazal for various reasons. The Rambam views the obligation to follow these rulings as part of the Torah commandment to listen to the Sanhedrin. One who doesn't observe dinim d'Rabanan is in violation of the positive and negative commandments of following the Sanhedrin just as one who refuses to submit to the Sanhedrin's authority in the first two aforementioned areas of halacha. It is this third ruling of the Rambam that the Ramban disagrees with, and argues that dinim d'Rabanan are not included in the pesukim in Parshas Shoftim that mandate the authority of the Sanhedrin. If the Ramban is correct, then what is the ultimate source for being required to follow dinim d'Rabanan? It is obvious that such an obligation must exist, yet its source is unclear.
Rav Elchonon Wasserman offers an approach to understand the role of dinim d'Rabanan according to the Ramban. It is incumbent upon everyone to do the will of Hashem. How do we know what Hashem wants of us? There are two ways to attain this knowledge. Hashem told us explicitly what He wants us to do and what not to do. The six hundred and thirteen mitzvos, with the interpretation of the Torah she'b'al peh, is the revealed will of Hashem. However, part of Hashem's will we are supposed to discover on our own. How can a human being possibly understand the will of Hashem without being told so explicitly? When two people know each other well it is not always necessary to express what one wants from the other. Spending time together and listening to one another will help develop a mutual understanding such that they are attuned to each other's wants even if they are not articulated. A similar relationship can be developed with Hashem, enabling one to understand what Hashem wants of us even if He chooses not to tell us explicitly. The Sanhedrin, which was comprised of the greatest talmidei chachamim of the generation, was able to discern the will of Hashem. By understanding the revealed word of Hashem, the Sanhedrin knew how to apply the will of Hashem in situations in which Hashem did not give a direct command. Dinim d'Rabanan are examples of that will of Hashem. There was no explicit command to light Chanuka candles or not to move muktza. Chazal, through their deep understanding of Torah, realized that those and other practices that are d'Rabanan are the will of Hashem.
This explanation of dinim d'Rabanan according to the Ramban is similar to other themes presented by the Ramban that focus on the unstated dimension of the will of Hashem. Commenting on the mitzva of resting on Shabbos and Yom Tov, the Ramban depicts how one could technically observe these mitzvos and completely undermine the sanctity of these days. Merely refraining from melacha by circumventing the actual halachic restrictions does not fulfill the will of Hashem. Chazal understood that for Shabbos and yom tov to conform to that will, various dinim d'Rabanan had to be instituted. What we sometimes describe as "not in the spirit of Shabbos" is actually a violation of Hashem's will even if not necessarily a breach of His actual law. A similar theme is expressed by the Ramabn in his interpretation of "Kedoshim Tihiyu - You should be holy." This is an all-encompassing requirement to live our lives in a holy manner, and not to satisfy ourselves will just not violating any explicit mitzva. The details of kedusha are not delineated, but Chazal guide us as to what appropriate behavior is that reflects the will of Hashem.
The letter of the law and its spirit are also present in our interpersonal relationships. Hashem gave us an entire body of intricate laws that govern our behavior to our fellow man. Yet, Chazal extol the significance of "lifnim mi'shuras ha'din", i.e. acting in a way that goes above the letter of the law. Hashem Who is rachum v'chanun expects us to act in a similar way. Although we are not specifically commanded to do so, doing the will of Hashem necessitates acting in such a fashion.
In our relationship with Hashem and with our fellow men we look to Chazal for guidance in fulfilling Hashem's will. Without proper Torah knowledge it is impossible to determine what Hashem truly wants of us. May we merit, in all of our endeavors, to reach the goal of "לעשות רצון אבינו שבשמים - To do the will of our Father in Heaven."
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