A theory is an <u><em>initial explanation</em></u>to an event/occurrence which is made <u><em>based on an educated guess </em></u>that can be considered as 'scientifically plausible' . (This means that we can't really hold a theory as fact since it hasn't been scientifically proven. )
The excerpt above fill all requirements of a theory:
1. It tried to explain a certain occurrence (how countries become wealthier their cultures shift to become more tolerant and open )
2. It is an educated guess (It is mentioned that Professor Chang has spent years studying human history and social change , this means that he had at least some level of expertise regarding the subject)
3. But it has not been really proven yet, since Professor Chang hasn't develop a scientific research to test the theory.
He is right because human intelligence may not be completely dependent on the grades and tests done at younger ages. Intelligence could come in many forms and in many different subjects. Not everything taught at school could be part of someone's intelligence, and that person could have strengths in other topics outside of the grades and tests done.
