Let's Talk About Sects
The Pharisees, Sadducees, and Essenes on law.
The [differences between the sects] are even more salient [than their similarities], owing to the fact that the primary sources often highlight them. Rabbinic literature, as noted, emphasizes halakhic differences, while the New Testament focuses on ideological and ritual issues separating the Pharisees and Jesus. [First century CE Jewish historian] Josephus first introduces the sects in his account of Jonathan [the Hasmonean leader who assumed the office of the high priest after the death of his brother Judah] (ca. 150) as follows:
Now at this time there were three schools of thought among the Jews, which held different opinions concerning human affairs; the first being that of the Pharisees, the second that of the Sadducees, and the third that of the Essenes.
As for the Pharisees, they say that certain events are the work of Fate, but not all; as to other events, it depends upon ourselves whether they shall take place or not. The sect of Essenes, however, declares that Fate is mistress of all things, and that nothing befalls men unless it be in accordance with her decree. But the Sadducees do away with Fate, holding that there is no such thing and that human actions are not achieved in accordance with her decree, but that all things lie within our own power, so that we ourselves are responsible for our well being, while we suffer misfortune through our own thoughtlessness. [JewishAntiquities 13.5.]
This is not the only place where Josephus focuses on philosophical differences between the sects; he notes other difference between them later on, in his account of Hyrcanus' rule. With the above distinctions in mind, we will next discuss the fundamental differences between the two sects that were based in Jerusalem.
The Pharisees and Oral Law
Perhaps the most outstanding characteristic of the Pharisees was their unique doctrine of the Oral Law, which they considered as binding as the written Torah itself. Josephus wrote:
For the present I wish merely to explain that the Pharisees had passed on to the people certain regulations handed down by former generations and not recorded in the Laws of Moses, for which reason they are rejected by the Sadducean group, who hold that only those regulations should be considered valid which were written down (in Scripture), and that those which had been handed down by former generations (lit., by the fathers) need not be observed. [Jewish Antiquities 13.10.]
The Pharisaic interpretations of the Torah, which ipso facto made up their Oral Tradition, thus carried an enormous degree of authority and legitimacy for those who accepted this claim. How exactly the Pharisees themselves would have formulated this idea is unknown, although later rabbinic tradition contains a number of statements in this vein.