Just like Shweta pointed - The lack of established principles & laws or concrete observations/citations & then gimmicks by self proclaimed maharaj's further mystify this already intriguing science. While I don’t wholly believe in it, I am quite interested in digging deeper into the subject!
I’m no scholar but my love for maths makes me believe that almost every phenomenon can be jotted down in an equation of some sort. Hence, I’m inclined that if such patterns can be identified and put into an equation, one can predict the outcomes and even influence it by manipulating the variables involved.
Reminds me of the beautiful script – “Final Destination” where they identify patterns (though non-mathematically) to understand death & try to cheat it. Similarly snips of “A Beautiful Mind” predicting the flight of a pigeon.
Coming to Astrology or associated sciences of Numerology, Palmistry, Face Reading, Handwriting Reading, Finger/Thumb printing (Nadi Astrology), Tarots etc – Albeit there possibly doesn’t exist a defined formula (may be yet) to put an equation, there definitely seem to be some fantastic studies of patterns of planetary movements, lines on the palms etc which if not explain or state for sure but tell in general behavioral and other patterns of life.
At the same time and often, I have observed that the predictions or forecasting is carefully done with an extremely generalized verbiage that if observed carefully they can be classified as “data” or “meta data” and then the beautiful human brain reads the circumstances and other influencing factors in such a manner that the individual begins interpreting the data into information fulfilling or relating to his individual needs.
Law’s of gravitation, escape velocity, etc were discovered only when we could sufficiently understand a phenomenon and derive an equation which gave accurate results. Today, we forecast weather, earthquakes, volcanic activities, spread of diseases, economy, stock market etc with significant accuracies simply because we’ve been able to create the equations around the observed patterns. Someday someone may develop an equation which will put to rest the mysteries of why Psychics can see the future but not predict it and likewise!
Coming back to the present, while I haven’t come across a scripture or living being who could guarantee his predictions with 100% accuracy, the fact that if we haven’t been able to comprehended it need not necessarily mean it is not possible, in itself is sufficient logic to intrigue me… and most of us alike!
I welcome your comments.
-Ashish
and 'yes' manglik issue will be discussed soon ... i am still studying that. 
