Whether Hellenistic Astrology was a Sudden or Gradual Development
© 2010 Curtis Manwaring
I don't see the question of whether Hellenistic astrology had a sudden onset, or whether it was piecemeal and gradual to be an either / or question that is mutually exclusive. There are too many different ideas out there as to what Hellenistic astrology is composed of and by these definitions, both have happened at the same time. It is natural to assume that most astrologers practicing from that era were not on the same page. The small group of people who appear to have worked elements of the middle Platonic school into Antiochus were doing something quite different from what Dorotheus, Ptolemy, Valens, etc. were doing, but most of them have many elements in common. Just as is happening in these days, the so called "founders" didn't agree with each other either (as you have "defined" them).
At some fundamental level each of you will have to decide whether to trust observation and empiricism or philosophy and consistency. I have chosen the latter because perception and observation has placed upon it demands that are too limiting (such as truly having observed adequately to see as a God), but with philosophy there are guidelines and ways to make the accidents of existence intelligible.