What is authoritative in the Talmud?

Question

Maimonides says:

However, all the matters mentioned by the Babylonian Talmud are incumbent on the entire Jewish people to follow. We must compel each and every city and each country to accept all the customs that were put into practice by the Sages of the Talmud, to pass decrees paralleling their decrees, and to observe their ordinances, since all the matters in the Babylonian Talmud were accepted by the entire Jewish people.

So according to my understanding, Maimonides says we should observe whatever the Talmud says. Yet we don't act upon every opinion found within the Talmud. So how do we determine which opinions are authoritative or not? And how do we know which opinions are accepted or rejected, and what to act upon or what not to act upon?

Answer 1

(My answer pertains to deciding between differing Halachic positions, rather than agadic/non-legal/non-halachic statements.)

Decision between multiple halachic positions is a fairly complicated matter. There are certain general rules for such decisions (כללי הספק) but they are not always hard and fast. Some of these rules are found in the Talmud itself, others in commentaries. Some good starting places are this article on Halachipedia, as well as the relevant chapter in R' Steinsaltz's Reference Guide to the Talmud. Depending on your comfort with (Rabinic) Hebrew, the literature cited as further reading in the Halachipedia article would provide a wealth of information, while a more concise presentation might be found in the Talmudic Encyclopedia (אנציקלופדיה תלמודית) under Halacha (Some of the volumes were translated, but I don't know how available they are. See here for a version of the hebrew article).