Josephus, himself trained among the Pharisees before later aligning with different factions at different points in his career, describes them alongside the Sadducees and the Essenes as one of the three principal Jewish schools of thought active in his lifetime, distinguished chiefly by their acceptance of a body of interpretive tradition, later called the Oral Torah, that they held to carry authority alongside the written Law of Moses. The Sadducees, drawn largely from priestly and aristocratic circles and controlling much of the Temple's formal administration, rejected this additional tradition and read the written Torah alone as binding, a narrower textual position that also led them to reject the Pharisaic doctrine of bodily resurrection, which the Pharisees defended as implicit within scripture even though it was not stated in the Torah in so many words.
Where Sadducee authority rested on Temple office and inherited priestly status, Pharisaic authority rested on learning and popular reputation, and Josephus records that the Pharisees enjoyed considerably wider support among the ordinary population of Judea than the more socially exclusive Sadducees did. This difference in social base helps explain why, when the Temple and its priesthood were destroyed in 70 CE, Pharisaic modes of authority, resting on interpretation and teaching rather than on a building and its cult, proved able to survive that destruction in a way Sadducee authority structurally could not.