Perhaps the most frequently asked question about Josephus concerns his reliability. But this deceptively simple question entails half a dozen others, each requiring a different answer.

Like all ancient historians, Josephus wrote to teach lessons: in his first book (The Jewish War), that the Judeans are peace-loving and civil; in other books (Antiquities of the Jews, Contra Apion), that they have the highest form of culture in the world. Although these were apparently the most important issues to Josephus, they tend not to matter much to those who ask about his reliability.

Scholars have often challenged Josephus’s claim that the First Jewish Revolt (66–70 C.E.) was generated by a small group of rebels; they point out that elements in his work—and general probability—suggest a larger war effort.1 But since Josephus’s real contention is not that the revolt was a minor affair but, rather, that a very few rebels gradually sold the rebellion to the masses—through early victories, some coercion and a menu of economic, political and religious enticements—his analysis of causes is hard to refute. So is he reliable or not?

Almost everything in Antiquities and Contra Apion, as well as a good deal of the Jewish War, comes from sources other than Josephus’s own experience. Were these sources correct in asserting that God created the world in 6 days, Methuselah lived for 969 years, Moses led the Egyptians against the Ethiopians, Saul conjured up the spirit of Samuel, Solomon wrote 3,000 books of parables, John Hyrcanus forcibly circumcised the Idumeans, a group of 72 Judean elders simultaneously produced identical Greek translations of the laws, or Alexander the Great read the Book of Daniel? We might answer these and hundreds of other such questions “no” and still know little about Josephus’s reliability. He simply depended on sources he trusted.

Did Josephus handle his sources according to the best standards of his day? Yes, by and large he writes as a good Hellenistic historian. For the Jewish War, he used the writings of the eminent Nicolaus of Damascus, imperial records and his own experience. It seems that his account of the revolt received endorsement from authorities such as Vespasian, Titus and Agrippa II. For Antiquities, Josephus used the Bible, which he trusted implicitly, along with old and respected texts such as Aristeas, 1 Maccabees, various works by gentile authors, Roman state documents and other plausible accounts.

His abilities as a critic surface most clearly in Contra Apion, in which he delights in exposing the contradictions of Egyptian authors. In Antiquities he does little criticism, since he has carefully chosen sources that will help him make his case for the superiority of Judean culture. Where those sources have survived, we can see that Josephus stays close to their content—though he freely paraphrases them to make his own points. He does not engage in any explicit critique of the Biblical accounts, but he does edit them in places by rearranging episodes and removing obvious difficulties (as with the list of Babylonian/Persian kings in Daniel); he also leaves some stories of the paranormal open to the reader’s assessment. In general, Josephus trusts ancient texts that have demonstrated, to him, truthfulness in prediction. But he occasionally cites different versions of the same event, and he openly challenges Nicolaus’s flattering portrayal of Herod. Although his critical tone varies, he plainly had some ability in this area.

Did Josephus write with the critical awareness of the modern historian? No. He is much freer in using material for his purposes. He even shows off his critical acumen by drawing different conclusions from the same evidence—in the Jewish War and Antiquities—a skill disdained by post-enlightenment historians but highly valued in antiquity.

Did Josephus invent stories and freely change his source material? Yes. Changes to his source material are easiest to spot in the overlapping material in the Jewish War and the later Antiquities, along with the autobiographical Life. Josephus considerably alters his portrayals of the later Hasmoneans, Herod the Great (and Herod’s father, Antipater), several Roman governors and his own role as leader of the Galilean revolt. In most cases, however, his changes involve splicing in new information and altering his evaluative tone; he still follows his sources’ content quite closely.

As for inventing stories: Few consider plausible Josephus’s claims in the Jewish War that the dried-up springs outside Jerusalem miraculously began to flow on Titus’s arrival, that a Roman ballista ball carried the fetus out of a pregnant woman’s womb for 100 yards, or that a cow gave birth to a lamb in the Temple. But these marvels are not typical of Josephus’s narrative, and one finds similar accounts in contemporaneous historians, such as Tacitus.

Did Josephus accurately describe places, buildings and institutions with which he was personally familiar? Yes and no. Josephus was not gifted with numbers. He offers some demonstrably incorrect distances in his homeland and elsewhere (though most are accurate), contradictory estimates of group sizes (the Jewish War conflicts with Antiquities), improbable time spans for his own genealogy and youth, and unlikely population figures. But such problems are rampant in the works of ancient authors, who had little opportunity to consult accurate figures. Moreover, ancient rhetorical custom tended to forgive big round numbers, and numbers are among the most easily corrupted features of a manuscript in transmission, especially where multiples of ten are involved. Josephus at least tries to justify some of the numbers he knows will seem unbelievable.

Josephus colors his narratives with background props drawn at least in part from his own experience. He discusses the fortresses built by Herod, the countryside of Judea and Galilee, and the Temple’s structure and furnishings. Perhaps because such things lend themselves to archaeological verification, they often provide the basis for scholars’ judgments about Josephus’s veracity as a historian. Josephus’s descriptions of the Essenes, of the popular influence of the Pharisees and of the social impotence of the Sadducees are sometimes thought to be testable on the basis of other surviving texts, such as rabbinic literature, the New Testament and the Dead Sea scrolls. A recent manual of ancient Jewish life by a noted scholar gives Josephus high marks for accuracy on the priests’ clothing and the Temple structure but challenges his descriptions of Essene theology (on the basis of the scrolls) and Pharisaic influence (in part because several “non-Pharisaic” immersion pools have been found).2 Archaeological work at Masada, Herodium, Caesarea, Qumran and Jerusalem’s southwestern corner has usually been taken as proof of Josephus’s basic accuracy in describing places and things.3

Several historians have challenged Josephus’s accounts of the burning of the Temple and the mass suicide at Masada. In the former case, the Byzantine writer Sulpicius Severus claims, contrary to Josephus, that Titus did order the Temple burned.4 In the latter case, the archaeological evidence of Masada does not match Josephus’s story in some particulars, and this disagreement has sometimes been taken to suggest that Josephus made up the entire suicide account.5

Nevertheless, it should not surprise us if Josephus turns out to be accurate, by and large, in his description of the world he knew. Archaeologists are delighted to find remains of the Masada, Herodium and Caesarea mentioned in Josephus’s narratives—but what else would we expect? Even if his writings are historical novels, playing fast and loose with the facts, we would expect them to refer to real situations, institutions and events.

But buildings and countryside are not the stuff of his history. Unlike archaeology, geology, paleontology and other ways of studying the past, history is concerned with explaining human actions: what people did and why they did it, their thoughts, aims and values. Josephus writes histories, offering comprehensive explanations of causes and effects. He wants to defend and celebrate Jewish culture to his Greek and Roman readers. If we could confront him with his error on the length of the Dead Sea or the orientation of a building at Masada, he would look at us incredulously and reply, “But that’s not what I was writing about!”