We had that discussion a while back - and for the reason you give I'd
say the issue is more complex, though on balance I agree that astrology
probably did not raise to the standard of science even when measured
against the understanding of science at the time. But it is a balanced
case, and some good historians of science have argued the opposite, that
some forms of astrology as practiced in some cultures was more akin to
the alchemy Newton practiced - a precursor to modern chemistry, not
something radically different.
Alexsander Birkmeyer's "Etudes d‘Histoires des Sciences" from 1977 makes
arguments similar to yours - that especially in hunter-gatherer
communities, or early agrarian societies, when you were born determined
quite a bit about you, simply by the effects of malnutrition. lack of
sunshine etc etc in your earliest months. There have been studies that
tested this, but could not find one offhand - problem is that as far as
I recall, there was no clear pattern.
There is also often an intermingling here between predicting nature and
people. If in that society storms, rivers etc are typically personified,
then "astrology" was a reasonable good predictor for when the next
flooding/rain season etc would come. And soem of them were remarkably
empirical in their approach, collecting data over centuries to adjust
and refine their predictions - the Babylonian diaries e.g. are as a
result a massive source of historical data from that time (great
discussion in U. Koch-Westenholz, Mesopotamian astrology. An
)introduction to Babylonian and Assyrian astrology (1995) Copenhagen
That these plausible patterns were then extended to (other)people was
of course in retrospect unwarranted, but driven in a way by a
(proto)scientific logic that extends by analogy an explanation that
works in one context to other contexts (Newton's principle of the
similarity of causes and their effects)
Another case that Birkmeyer uses is that of Keppler, who kept detailed
notes of his predictions and checked up on their success - and making
changes in his methods when they failed. This was not uncommon among
Renaissance astrologers
The majority of historians of science I think come down on the other
side, A. C. Crombie's book "Augustine to Galileo: The
History of Science A.D. 400–1600 decries astrology as superstitition
that was incompatible even with the science of the 4th century.
On balance, I'd agree with them. Mainly because the problems with
astrology had been known even by their contemporaries, and were never
satisfactorily addressed - yes, there was refinement on the basis of
observation, but no answer to obvious questions like: How can it be that
in a battle thousands die, all born on different days (so already
Cicero) But it isn't a slam dunk either, and a lot depends on a) what
culture and time you think of and b) your preferred definition of
science (which renders part of the discussion an issue of semantics)