In psychological astrology we learn that the jungian model of the four psychological types (sensation, intuition, feeling and thinking) corresponds closely to the four astrological elements: earth, fire, water and air. Following this model, psychological astrology claims that air is friendly with fire with water being its true opposite, while earth is friendly with water with fire being its true opposite. On the face of it, this distinction seems to be true. Indeed, air hates the subjectivity of feeling and fire hates earth's lack of vision.
In traditional astrology, however, the four basic qualities are hot, cold, moist and dry. Fire signs are hot and dry, water signs are cold and moist, air signs are hot and moist and earth signs are cold and dry. Which means that for traditional astrology air is indeed friendly with fire and water is indeed friendly with earth, but fire's true opposite is not earth but water and air's true opposite is not water but earth. Hot and cold are the "active" qualities, indicating high levels of energy (fire) or low levels of energy (cold), whereas moist and dry are the "passive" qualities, indicating a need to connect (water) or a need to separate (dry). Air does indeed want to connect, like water, but does it through intellect, not emotion and fire does indeed want to stay separate, like earth, but strives to separate by constantly moving, unlike earth which prefers to stay put.
So, how do we solve this dilemma when both sides seem to have a valid point? We could start by defining the term "opposite". Does opposite mean mutual hatred or does it mean indifference through complete lack of understanding? Who do we really hate? The one with whom we have nothing in common or the one who goes after the same things we do but in a completely different manner? Isn't it the latter one? It's only the ones who have the same goals as us, but propose a different approach thereby putting us in the wrong, that are capable of arousing in us such a strong feeling as hatred. So, based on hatred, psychological astrology is right. If, however, opposite means "completely different", then traditional astrology is right, because it's fire that has nothing in common with water and it's earth that has nothing in common with air.
Keep in mind that in the psychological model, it is the "active" quality (hot, cold) that needs to be different, for it to be able to produce hatred, while the "passive" one (moist, dry) needs to be the same. If the goal is different (passive quality) and the approach (active quality) is the same, there is no emnity. Just like athletes playing a different sport. There's no real competition.
