Originally Posted by
Singu
...Because you clearly don't even understand what a "theory" means.
Your view of "testing" the theory is to see if it is "accurately describing" the observation of reality or not. Your view of a (successful) "theory" is if it's accurately descriptive of multiple people's observations.
But that creates a new problem: How should we know about what the person is going to do in the future? Or how should we know about what the person's going to do in different, yet-to-be-observed situations? How do we even know that what we have observed of the person so far, is the entirety of a person's personality?