What Jung did was, he basically made a bunch of observations of people. And he may have made a faithful recreation of those observations. He may have made an astute observation that is true to the fact.
So Jung noticed that some people were more emotional than others, so he generalized this pattern and called them Feeling types. And he also noticed that some were more thoughtful or quieter than others or whatever, so he called them Introverted types. And so you put them together, and they were Introverted Feeling types, or Fi types (this is a gross simplification, you can make it as complex as you'd like).
Basically, he made a neat system of categorization, and he categorized people accordingly. This is all good and fine.
But the question is, so what? All he did was made a bunch of collections of observations, which is neatly categorized and ordered, but he never made a system of a theory of such. He didn't take a guess at why and how that was such a case. They only became certain data points, and data in of itself don't have any meaning, until we interpret them through a theory. What we are really interested in is, how do something work, and why. And we can use that information to predict the future, if we wanted (to solve certain problems).
But we don't have that. What we have instead, is the assumption that since a type has been this way, they will always remain that way in the future. But that is unlikely to happen, because we are not animals with limited sets of actions, where we can't do no more than what we are programmed to do. What separates the animal from humans is our creativity, which is our ability to do or come up with something that has never been done before. And that something, is the key to predicting the future, since the future is something that has not occurred yet. That something is our ability to explain how something works. We are by nature, universal explainers that can explain both our own selves, and the workings of the entire universe.
So Jung noticed that some people were more emotional than others, so he generalized this pattern and called them Feeling types. And he also noticed that some were more thoughtful or quieter than others or whatever, so he called them Introverted types. And so you put them together, and they were Introverted Feeling types, or Fi types (this is a gross simplification, you can make it as complex as you'd like).
Basically, he made a neat system of categorization, and he categorized people accordingly. This is all good and fine.
But the question is, so what? All he did was made a bunch of collections of observations, which is neatly categorized and ordered, but he never made a system of a theory of such. He didn't take a guess at why and how that was such a case. They only became certain data points, and data in of itself don't have any meaning, until we interpret them through a theory. What we are really interested in is, how do something work, and why. And we can use that information to predict the future, if we wanted (to solve certain problems).
But we don't have that. What we have instead, is the assumption that since a type has been this way, they will always remain that way in the future. But that is unlikely to happen, because we are not animals with limited sets of actions, where we can't do no more than what we are programmed to do. What separates the animal from humans is our creativity, which is our ability to do or come up with something that has never been done before. And that something, is the key to predicting the future, since the future is something that has not occurred yet. That something is our ability to explain how something works. We are by nature, universal explainers that can explain both our own selves, and the workings of the entire universe.