Many Orthodox Jews are convinced that the basic tenet of Judaism is the acceptance of the idea that both the Five Books of Moses, the written Torah, and the rules in the Oral Torah were given by God to the Israelites on Mount Sinai. They hold this belief despite the fact that: (a) The Five Books of Moses does not claim that God gave the Torah to the Israelites at Sinai, just the Decalogue, commonly called The Ten Commandments, and it does not mention the existence of an Oral Torah, or even hint that such a system exists. (b) The Five Books of Moses contains the history of the Israelites and the laws given to them long after the Israelites left Sinai with no indication that they returned to Sinai. (c) Many laws in the Oral Law contradict what is in the Books of Moses. (d) It is clear that many if not most of the laws in the Oral Law were clearly promulgated long after the Israelites entered Canaan.
For example, the Torah states that people are punished “an eye for an eye.” Meaning if you knock out a person’s eye, you are punished by having your eye removed. Ancient Jewry, possibly including rabbis, saw that this punishment was inappropriate, and declared that the punishment is monetary compensation equal to the value of the eye, the individual’s pain, his doctor bills, his loss of wages from work, and the embarrassment he suffers. Those who insist that the Oral Law was delivered at Sinai when the Torah Law was declared, seem to envision God saying, “although I am demanding in the written Torah that the punishment is the removal of an eye, I really do not mean what I said, I want an elaborate payment procedure.” It is difficult to believe that God took such an approach.
As proof that there had to be an Oral Torah given with the written text is the argument that much of the Five Books of Moses are unclear and needed an oral interpretation. Most often cited is the command in the Decalogue, “you may not do any kind of work” on the Sabbath. The argument is made that the term “work” is unclear, the text does not state what is prohibited and needed the Oral Law to detail 39 types of activities. Actually, this point can be answered. People know what work is and the Torah was allowing each individual to decide what work should be avoided, much like the current Christian idea of refraining from work on Sunday.
Thus, there are two approaches: that an Oral tradition/law was given at Sinai together with the written Torah and the view that the Oral Law was a later development in Judaism, interpretations that changed what the Torah demanded to fit the changes in circumstances. These changes, according to the later view, where based upon what the Torah hints. For example, there are so many restrictions placed on sacrifices that it is clear that the Torah reflected the idea that God “allowed” sacrifices because of the ancient need that people had, but preferred that sacrifices cease.
Rabbi Chaim H. Schimmel takes a third approach in the reprinting of his earlier book “The Oral Law” (Maggid Books, 2019). While leaning toward the traditional approach that God gave the Israelites two Torahs, he agrees that the rabbis added to the Sinaitic Oral Torah. “In this book we make it clear that although the law revealed at Sinai always reigned supreme, the sages made a massive contribution to its development.” He clarifies this with a restriction, “the sages acted only within the rules and limits laid down by the Sinaitic tradition. Further, they did not aim to adapt Torah to changing times, but rather to preserve Torah in changing times.” Much of the contributions of the sages were “interpretations,” but there was also new “legislation.” But, he insists, this new legislation is based on interpretation “inspired by ruach hakodesh,” divine inspiration.