Note: This is part one of a series on issues relating to Luke’s statement that John the Baptist began his ministry “in the fifteenth year of the reign of Tiberius Caesar” (Luke 3:1).
In the past, New Testament Chronologists have argued that “the rule of Tiberius” began in October of 12 AD, the middle of 13 AD, or August of 14 AD. History does give us enough facts to judge the merits of each case, and decide for ourselves. But knowing which date Luke chose to count from is a whole other issue. First, then, we must begin with the facts of Roman History, as succinctly as they might be stated:
Tiberius came home from Germany to a Triumphal parade in October 12 AD. At that time, the increased powers he’d held over Gaul & Germany were expanded geographically to include all the provinces. But it seems most likely that none of his special powers extended to Rome itself at this time.
In mid-13 AD, Augustus had the Senate increase Tiberius’ special powers to equal those of Augustus. This most likely is when Tiberius’ “imperium” was expanded to include the city of Rome as well. Effectively, for legal purposes, Rome had two Emperors at this point. Practically, however, Augustus was still calling all the shots. Legally, you could say Tiberius was “ruling”. In all practical fact, however, he was not.
The best evidence for concluding that Tiberius did not receive imperium over Rome itself until mid-13 AD is the fact that Tiberius immediately left the city at this time (to oversee a census of Italy). This principle of separation was enacted during the first and second triumvirates – the basic idea being that “co-Emperors” were likely to disagree and therefore should carry on separate duties in separate parts of the Empire as much as possible. And since Tiberius had been in Rome with Augustus all winter and spring, it looks strongly as if the full imperium “equal to that of Augustus” and as “colleague in the Empire” was not begun in late 12, but in mid 13.
Finally, Augustus Caesar died on August 19th, 14 AD. At this point, Tiberius began to exercise full Imperial powers as Emperor. Actually, at first he didn’t do much, but what little he did shows clearly that the Imperial power was already fully his. Scholars agree that Tiberius was Emperor on August 19th, and that the Senate debate of September 17th must be explained in other ways.
These facts of Roman History are mostly and fairly straightforward. The only question is how to label them. From our current vantage point, it appears Tiberius began legally “co-ruling” with Augustus in mid-13 AD, but only began ruling in all practical factuality on Augustus’ death in August, 14 AD. Scholars today naturally acknowledge the subtleties of this complex situation, but ancient writers took more simplified views. Our leading sources, Tacitus & Dio Cassius simply counted from the death of Augustus.
Our final fact is that Luke’s Gospel refers to “the rule of Tiberius” without telling us whether Luke chose to count from Augustus' death in 14 AD or from the joint rule of 13 AD. The second option would be fairly unique, but any comparison with other ancient writers suffers slightly because they wrote many decades after Luke's heyday in the 50's & 60's AD. This uncertainty about Luke's annalistic frame of reference is a key pivot point for New Testament Chronologists.
Past efforts to claim Luke placed the joint rule in late 12 AD should probably be credited merely as the overstretching of hopeful apologists – which they were at the very least. Although classical scholars have admitted that 12 AD cannot be ruled out entirely, it seems extremely unlikely (as shown above). Besides, it’s enough of a stretch to even suppose that Luke counted from the joint rule at all (even placed more securely in 13 where it probably belongs). Counting from the joint rule would be a unique standpoint among ancient writers which, although it cannot be ruled out, is far from the strongest likelihood.
The most likely option is to believe Luke began counting from August 19th, 14 AD, like the later ancient writers also did. The less likely option that Luke counted from 13 AD can neither be ruled out or accepted on any solid grounds. But there are strong reasons to discount the option of 12 AD on the balance of evidence from Roman History. Therefore, until some new evidence appears, New Testament Chronology should proceed as if Luke began counting the years of the Rule of Tiberius from 14 AD.
My next post will deal with the question of whether Luke counted chronologically or inclusively.