Criticism of Ptolemy's Canon

Ever since its founding in the late 19th century the Watch Tower has repeatedly flip-flopped in its use of Ptolemy's Canon.

Three Worlds (1877) and Millennial Dawn II (1889)

As seen in the section on Russell and Barbour, Ptolemy's canon was supposedly used by Barbour and the Russell as the source of their chronology [1]. 194 [2, p. 79].

The fact that the first year of Cyrus was B.C. 536, is based on Ptolemy’s canon, supported by the eclipses by which the dates of the Grecian and Persian era have been regulated.

With these facts before us, we readily find the date for the beginning of the Gentile Times of dominion; for the first year of the reign of Cyrus is a very clearly fixed date — both secular and religious histories with marked unanimity agreeing with Ptolemy’s Canon, which places it B.C. 536.

The Watchtower (1952 - 1968)

The Watch Tower history section shows that from 1952 onwards the Watch Tower began to use the date 539 BC for the fall of Babylon [3, p. 490], supposedly based on the Nabonidus chronicle:

The fixing of 539 B.C.E. as the year when this historical event occurred is based on a stone document known as the Nabonidus (Nabunaid) Chronicle.

But the Nabonidus Chronicle doesn't actually contain anything datable to the Julian calendar; the footnotes in each of these issues of the Watch Tower instead cite Parker and Dubberstein's tables, which were in turn principally based upon Ptolemy's canon [4, p. 8], and would have been used to map the date in the Nabonidus chronicle to 539 BC:

The general basis for the chronology of the period here treated is furnished by the Ptolemaic Canon, with help from classical sources.

The Watchtower (1969)

Despite having explicitly and implicitly based their chronology on Ptolemy's canon until this point, the 1969 article 'Babylonian Chronology — How Reliable?' [5, p. 90] starts to question its reliability:

On the other hand, those who hold to a strict Ptolemaic reckoning are obliged to explain a sizable gap of their own. This gap develops when they attempt to harmonize Babylonian and Assyrian history so as to arrive at 625 B.C.E. for the start of the Neo-Babylonian period.
The Babylonian Chronicle states that Nineveh, Assyria’s capital, fell to the Babylonian forces in Nabopolassar’s fourteenth year. Following Ptolemy, the secular historians date that event in 612 B.C.E. At the same time, on the basis of astronomical calculations, they also hold to the year 763 B.C.E. as an absolute date representing the ninth year of Assyrian king Assur-dan III. So, they should be able to count forward from that year and show that Assyrian rule at Nineveh did extend as far as 612 B.C.E. But can they? Well, with the help of eponym and king lists and other source material, they manage to set up a chronology that reaches as far as 668 B.C.E., the year they assign for the start of Ashurbanipal’s reign. But from that point forward there is considerable confusion.

The Watchtower is correct to state that Ashurbanipal's accession year is accepted to be 669 BC, but that the length and circumstances of the end of his reign remain disputed [6, p. 135] [7, p. 1]. But they then suggest that using the chronology of Ptolemy's canon leads to an unexplained 'gap' in the reign of Sinsharishkun:

As might be expected, the above sources also give varied dates for the reign of Ashurbanipal’s probable successor, Ashur-etillu-ilani. And so, too, for the reign of Sin-shar-ishkun, apparently the king at the time of Nineveh’s fall. Some historians extend this last king’s reign for as long as eighteen years, though dated tablets have been found only up to his seventh year.
Thus historians are willing to exhibit much flexibility in order to hold to both the Ptolemaic chronology and their pivotal date of 763 B.C.E., even to the point of conjecturing longer reigns for these final rulers of the Assyrian empire than the evidence at hand will support. They have an awkward gap on their hands—one that is not easy to fill.

This is odd, because the dispute among scholars concerns the extent to which the reigns of the late Assyrian kings (Ashurbanipal, Ashur-etil-ilani, Sinsharishkun and Sin-shumu-lishir) must overlap, not whether there is any gap between them. It is generally accepted that Sinsharishkun's accession year occurred somewhere around 627 BC (the year prior to Nabopolassar's accession) [7, p. 2] [8, p. 246]. The evidence includes:

• The Uruk King List names Sinsharishkun as king in the year prior to Nabopolassar.
• The chronicle BM 25127 (lines 1-14) names Sinsharishkun as being in command of the Assyrian army in the months prior to Nabopolassar's accession [9, p. 71].

The Watchtower itself points out that Sinsharishkun died during Nineveh's fall (see the chronicle BM 21901) which is dated to Nabopolassar's 14th year in 612 BC. So we can now see why Sinsharishkun's reign in Assyria must span approximately 16 years, it has not been 'extended' without evidence.

The dated texts from the first 7 years of Sinsharishkun's reign are those found in the cities of Babylon, Nippur, Uruk, Sippar [10, p. 17], it was during these 7 years that Nabopolassar king of Babylon and Sinsharishkun king of Assyria were at war. The cities were under siege and changed control multiple times [11, p. 85], but by Nabopolassar's 7th year Assyria had 'lost its last foothold in Babylonia' [8, pp. 251, 265]. So while there is indeed a 'gap' in the texts dated to the later part of Sinsharishkun's reign, but this is simply because he was no longer king of the Babylonian cities anymore; there is no indication Ptolemy's canon is incorrect.

The Watchtower (1971)

In a 1971 article The Watchtower ended the illusion that the year 539 BC could be found from the Nabonidus chronicle. But despite having attempted to discredit Ptolemy's canon only two years before, they returned to directly referencing it as a source for their chronology [12, p. 316]:

Also other sources, including Ptolemy’s canon, point to the year 539 B.C.E. as the date for Babylon’s fall.

Watchtower (2011)

In the 2011 article 'When Was Ancient Jerusalem Destroyed?' The Watchtower returns to criticising the canon, implying that by omitting certain kings its chronology might not be accurate [13, pp. 30–31]:

How does Ptolemy’s list compare with that cuneiform record? The box “How Does Ptolemy’s Canon Compare With Ancient Tablets?” (see below) shows a portion of the canon and compares this with an ancient cuneiform document. Notice that Ptolemy lists only four kings between the Babylonian rulers Kandalanu and Nabonidus. However, the Uruk King List​—a part of the cuneiform record—​reveals that seven kings ruled in between. Were their reigns brief and negligible? One of them, according to cuneiform economic tablets, ruled for seven years.⁸

There is also strong evidence from cuneiform documents that prior to the reign of Nabopolassar (the first king of the Neo-Babylonian period), another king (Ashur-etel-ilani) ruled for four years in Babylonia. Also, for more than a year, there was no king in the land.⁹ Yet, all of this is left out of Ptolemy’s canon.

Why did Ptolemy omit some rulers? Evidently, he did not consider them to be legitimate rulers of Babylon.¹⁰ For example, he excluded Labashi-Marduk, a Neo-Babylonian king. But according to cuneiform documents, the kings whom Ptolemy omitted actually ruled over Babylonia.

8. Sin-sharra-ishkun ruled for seven years, and 57 economic tablets of this king are dated from his accession year through year seven. See Journal of Cuneiform Studies, Volume 35, 1983, pages 54-59.
9. The economic tablet C.B.M. 2152 is dated in the fourth year of Ashur-etel-ilani. (Legal and Commercial Transactions Dated in the Assyrian, Neo-Babylonian and Persian Periods​—Chiefly From Nippur, by A.T. Clay, 1908, page 74.) Also the Harran Inscriptions of Nabonidus, (H1B), I, line 30, has him listed just before Nabopolassar. (Anatolian Studies, Vol. VIII, 1958, pages 35, 47.) For the kingless period, see Chronicle 2, line 14, of Assyrian and Babylonian Chronicles, pages 87-88.
10. Some scholars contend that certain kings were omitted by Ptolemy​—who supposedly listed only kings of Babylon—​because these were called by the title “King of Assyria.” However, as you will note in the box on page 30, several kings included in Ptolemy’s canon also had the title “King of Assyria.” Economic tablets, cuneiform letters, and inscriptions clearly reveal that kings Ashur-etel-ilani, Sin-shumu-lishir, and Sin-sharra-ishkun ruled over Babylonia.

The Watchtower is being disingenuous here because the answers to why these kings were omitted by Ptolemy's canon is available in the very sources they have cited. Ptolemy's canon only lists one Babylonian king per year, it does not include contested kings or those who just ruled for part of the year. When the full information from the texts is shown the solution is obvious:

As already explained above, the reigns of the Assyrian king Sinsharishkun and Babylonian king Nabopolassar overlapped; whilst at various points during the first 7 years of his reign Sinsharishkun besieged and controlled various Babylonian cities, at no point was he the sole uncontested king of Babylonia, he died during Nabopolassar's 14th year.

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