The Oral Law: The Rabbinic Contribution to Torah sheBe'al Peh

Since the Torah was given to all of Am Yisrael at Sinai, how did disputes as to its meaning arise? How did the Sages act when new situations arose that were not provided for in the tradition? What is the difference between Rabbinic interpretation and Rabbinic legislation, and to what extent are these guided by logic or moral reasoning? To what extent did the Sages enjoy the power to interpret tradition and legislate? Did the Sages rely on legal fictions to change the law?
These questions, am...