If you want to know what the future holds just read the Bible.
Whether you believe it or not it has never been wrong in all of its forecast.
The bible is in the same camp as astrology and many other mystical beliefs, it's almost impossible to be completely wrong. Essentially all these methods are incapable of making specific predictions, they generalize and rely on liberal interpretations drawing inferences with everyday events. Moreover, people always remember the things which fit and forget those which don't confusing causation and chance.
Theories only stand up if they make proposals that can
later be tested by observation ?
This is very similar to Karl Popper's philosophy
“The criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.” however all theories which are correct are not necessarily scientific. Is therefore a trading system scientific, or would it fall into one of the unscientific camps below?
Astrology doesn’t pass the scientific test. It escapes being falsified by being vague. Vague predictions are irrefutable. Ex. “You will learn something today.” Can you imagine a day in which you learn absolutely nothing? No.
The Marxist theory of history made predictions and was falsified. But, the holders of this theory reinterpreted their theory and evidence, in other words, they made ad hoc changes to the theory. If I change my theory every time I get falsifying evidence, then it becomes impossible to refute.
Psychoanalytic theories are straightforwardly not testable, or irrefutable. This is not to say that they aren't useful or that they fail to describe some parts of the world accurately. But, it is not science.
Personally I think that trading could be scientific, despite being horribly complex to analyse. The problem is that most people are very unscientific in their approach, they try to find reasons why a particular TA system works, citing a few examples or examples which could be intepreted in many ways, rather than saying, but if you drew the line here or took this period you would lose money! You must include everything, the good bad and the ugly! Refutation isn't just about finding fault, it can add strength to a theory, we know trading systems must lose some of the time, the trick is to find out how much and often so we know how much capital to place on trades to obtain a certain return for the risk we take.