Astrologers are eager to tell you that they can predict the future, unfortunately their track record leaves much to be desired. There are times though, when their efforts bear fruit. The believers are quick to defend them and the skeptics are quick to debunk them. The truth does not lay somewhere in the middle but in understanding the realities involved.
Astrology can for purposes of making a point, be compared to predicting the weather. A weatherman can with reasonable confidence tell you months in advice that in July and August the temperature in south Florida will be in the 90 degree range during the day and the 80 degree range at night. They can also say that the chance for a hurricane occurring will be strongest in the first two weeks or so of September. Hurricane forecasters can now with amazing accuracy predict the path of a formed hurricane with computer simulations based on upper level air masses. They always in their predictions err on the side of caution, never forgetting the unpredictability of hurricanes. As the hurricane approaches they can amend their predictions and narrow down where the storm will hit. By monitoring the wind speed, size and other variables they can predict the potential damage the storm will do.
So too can an astrologer make an educated prediction. Much like the weatherman, who has a difficult if not impossible task trying to predict where any hurricanes will hit months in advance, the astrologer will have tremendous difficulty judging what part of ones life will be affected by a predictable crisis. Just as weathermen would be hard pressed to tell in advice the result of a storm on specific neighborhoods. (remember Andrew) An astrologer would be hard pressed to tell what specifically will happen.
Weather predictions are based in part on cumulative data acquired over years of observation. Astrological predictions are based in part on the same theory.
Hurricanes will affect people in part, according to their preparation for the storm. Predictable events will also be modified by the persons previous preparation in life. For example, a prediction of a storm may be made if the planet Pluto is approaching by transit (its 360 degree cycle around the sun) a persons natal sun. (the degree that the sun was when the person was born)
Obviously many people were born with the sun in the same place. Just how that person will be affected is much like a weather prediction. Why Hurricane Andrew hit some streets harder than others is impossible to predict. Nonetheless the storm was real. A prediction of difficulty by an astrologer would be fundamentally accurate. Predicting how it will hit and the damage it will do is much harder. As with Hurricane predictions, there is always that something else. The random unpredictability contained within the situation that can only, like quantum physics give us probabilities. The astrologer can glean insights by studying the natal chart and learning what environment the person has lived in. An astrologer also must have an idea what level the person lives at, As Carl Jung put it: What happens to a person is characteristic of himself.
People have a certain nature, once an astrologer grasps the patterns and traits in a life he or she can gauge predictive influences more precisely. This is a daunting task for even the most accomplished astrologers and a clear misrepresentation by those that claim they can predict our lives without knowing at what level we live. (There are times when the a chart reflects a period of benelovence or challege, breakthroughs or blocks. While these may be relativly apparant, still the degree and area would be comenserate with the the level at which one lives. More often than not many different themes occur at the same time, blending with the free will of the person. Clearly not an easy task even if the astrologer asks questions and gains insight into the life of the person.)
In a nutshell, astrology is the art of observing what happened in the past, when a pattern of planets were in a certain position. Finding patterns, documenting the results and using them to predict the future and the personality that reflects these positions. The next step is to observe the persons life and see how these patterns work in their specific circumstances and enviroment, and then come to an understanding of how the person relates to the configurations.
The history of these observations has left a pattern of observable effects that one can work with to understand a person. The ability to be precise is limited by the tremendous amount of variables and the individuality of each person. Any reasonable practitioner with real knowledge of astrology, who has observed the events in their own and their clients lives over a period of years can attest to the merit of the results. They can say with confidence that they can give insights and background information that will be of value. They also recognize the difficulty.