The Talmud as a whole, and especially the Mishna, is first and foremost a vast corpus of Jewish law. Yet in studying this wide-ranging text, one would be hard-pressed to find any material on Jewish legal theory. Jewish law is primarily case-based, and a legal theorist would find the Talmudic approach most unusual.
"G-d wanted to give merit to the Jewish people; therefore, He increased for them Torah and mitzvoth". A Jewish way of life offers so many opportunities for mitzvoth. We accumulate mitzvoth--and hence, merit--for such things as saying good morning to a passerby, conducting a business transaction honestly, showing up in shul to hear shofar, eating a meal on Shabbat, and many other activities that are both easy and enjoyable.
"Rav Yirmiya ben Elazar said, there are three entrances to Gehenom: one in the desert, one in the sea, and one in Jerusalem" (Eiruvin 19a). The Talmud finds scriptural support for this from the narrative of the earth swallowing up Korach and his supporters in the desert, the description of Yonah crying out to G-d from the depths of the ocean, and from the verse in Isaiah, "Whose fire is in Zion, and His furnace in Jerusalem" (31:9). The exact nature of Gehenom need not concern us; it is the path leading to it that should worry us more.
ba'al tashchit, the wanton destruction of property, are recorded specifically in regard to a war situation (how much more was human life to be valued); sanitation standards had to be enforced; and it was the Torah's fear of rape that led to the law of a captured woman (see Devarim 21:10-15).
It is well known that the halacha, with rare exceptions, follows the opinion of Beit Hillel over that of Beit Shammai. What is less well known is why this is so. The Talmud notes that "a heavenly voice declared; these and those are the word of the living G-d, and the halacha follows Beit Hillel" (Eiruvin 13b).
"When I [Rav Meir] came to Rabbi Yishmael, he said to me, 'My son, what is your occupation?' I told him, 'I am a scribe', and he said to me, 'Be meticulous in your work, for your work is the work of heaven—perhaps you will omit one letter or add one letter; you would thereby destroy the entire world'" (Eiruvin 13a).
Traditionally, Jewish law allowed for a good deal of local autonomy in the application of Jewish law. While questions of national import were to be decided for all by the Sanhedrin, there was, for the most part, little centralization of Jewish law. Hence, the concept of mara d'atra: the rabbi of a community who, due to his intimate knowledge of the community, was better able to rule on a given question, even if others who did not live in the community were greater in stature.
The halachic system, like most other disciplines, has both a theoretical framework and a practical application--and the two do not always coincide. While this may be frustrating at times, no system can operate in an abstract world, devoid of a multitude of factors that may impact on practical rulings. An important measure of a great posek(decisor of Jewish law) lies in his ability to apply his expert knowledge in halacha from the abstract world to real-life situations.
It is impossible, at least from a Jewish perspective, to understand the Bible without the tools to interpret the text. It is this "reading between the lines" that brings the Torah to life, allowing for its multiple meanings and eternal relevance. The most famous formulation of the rules of these interpretations--and there definitely are rules--is the 13 hermeneutic principles enumerated by the second-century sage, Rabbi Yishmoel. Its importance is such that it has made its way into our daily prayers.
"A pot with two cooks is neither hot nor cold" (Eruvin 3a). This popular folk saying is used by the Talmud to explain Rava of Parzkiah's view regarding the validity of an eiruv.