There is no complete theory, because having a complete theory would require a complete theory about cognition. But the general understanding is that horoscopes

There is no complete theory, because having a complete theory would require a complete theory about cognition. But the general understanding is that horoscopes and astrology play into the fallacy of personal validation. People are bad at evaluating how generic certain descriptions are. It is a well researched and replicated result. The arguments supporting horoscopes and astrology are also written in a way to make them impossible to disprove, making them unscientific. https://en.wikipedia.org/wiki/Barnum_effect https://en.wikipedia.org/wiki/Barnum_effect