As to "secular" dating - isn't it obvious that there would be no "biblical" dating without it? The bible itself has nothing to fix time in relation to our present calender unless you can find a proven and well-documented historical date that is also clearly referenced in the bible.
As far as the events concerned here, there were a lot more "world shaking" events in this time period than the so-called exile of the Jews.
For example: Every reference I can find says Nebuchadnezzer began his rule in 605bce. They further indicate that he defeated Pharoah Necho earlier in 605bce. The recently discovered Bablyonian Chronicle (found about 1956) states that Nebuchadnezzar was first made a general in the 19th year of his father's reign (Nabopolasser) which would correspond to 607bce.
The date for Pharoah Necho's defeat at Carchemish (605) would then follow, rather than predate, Jerusalem's destruction if you accept the WTS 607. This is an anomaly if you follow the historical sequence. First, Egypt is defeated. Then, full of hope, the Jews revolt. Later, Jehoichin is captured. Years later, Zedekiah makes another revolt, ending in Jerusalem's destruction. This is in 586/587bce, the 19th year of Nebuchadnezzar.
Incidentally, it is generally thought (and I believe the WT agrees here) that Josiah of Judah was earlier defeated by Necho and Megiddo and was killed in that battle. This is dated at 609bce.
What bothers me most about this jump backwards of 20 years for the temple destruction, is that not only just the destruction of the temple is moved, but it requires us to move every single important date in human history from 625 to 525 bce by the same 20 years, if you want to maintain the historical sequence of events.
Maybe what the WT needs to do is pick a new "beginning" and "end" for the seventy years, to make it work. Maybe a symbolic one. After all, fullfilment of the derived 20th century dates from 607bce is so obviously trashed by now that they could set this straight (like the 7000 year creative day) and probably nobody in that org (but our scholar) would even notice...
For me, it doesn't make a hill of beans if the date was 607, 606, 587, 586, or whatever. But it does freak me out to completely reorder all the historical sequences of the day to stubbornly count backward 70 years from a date you arbitrarily pick!
James -
I only wrote this because the Theocrat never would tell me when Nebuchadnezzar died.