We say “astrology” as if it were one unified entity, but of course it is not. How many house systems are there? Do we use asteroids or not? What about Uranus, Neptune, and Pluto? – many traditionalists prefer to ignore them. Meanwhile, Uranian astrologers use hypothetical planets that no one has ever seen – Poseidon, Zeus and so on – and swear by them. I hear they get good results too. As an evolutionary astrologer, much of what I say revolves around the south node of the Moon – but most commercial astrology programs do not even show its position unless you ask them to.
Even more fundamentally, is astrology about the stars or the seasons? To a Vedic astrologer, the sign Aries and the constellation Aries are the same thing – but not to a western “Tropical” astrologer, where Aries starts with the northern Vernal Equinox, which has actually drifted back into Pisces over the centuries.
To put it charitably, astrology is a “big tent.” To put it more pointedly, the many different branches of astrology contradict each other in fundamental ways. Inevitably, this reality leads to the question of which form of astrology is “the right one” – and there begins a slippery slope.