Do you know what is, at least for me, the most common answer when I ask people about the extroversion and introversion? That they are sometimes extroverted and sometimes introverted. And then I have to explain that it is quite likely that they are right, but that does not mean that the conversation about extroversion and introversion is misplaced.
I mean, when we talk about the Big Five, then the distribution is kind of similar to the normal distribution, so most people are somewhere in the middle. Not many people are pure extroverts or pure introverts.
The things are a little different in the MBTI, where the division between the extroverts and introverts is more pronounced. If it is measured by the letters, then it has the similar distribution the the Big Five. But if it is measured by functions a person uses, which is my preferred method, then people are either clear introverts or clear extroverts, because their strongest function is either introverted or extroverted.
But if it is combined with the Bebee's theory about the connection between the position of the function and archetype, then it can be shown that the function that represents our ego or ourselves, and the function that represents our primary relation with the world are the opposite. So people that are introverts, would have a extroverted primary mean of dealing with a person and vice-versa. This is what the first two functions represent.
So for example as ISFP would be introverted toward themselves and extroverted toward others. While ESTJ would be extroverted toward themselves and introverted toward others.
Even so, being extroverted toward other people still means that a lot of times these people on average appear more introverted. It is just that they are perfectly capable of using their extroverted function to deal with the world. It just usually gets channeled through the first function, that is why they (actually we) still appear more introverted.
But I can explain this on a couple of examples. The first one would be me, who is an INTP. So I would introverted toward myself and extroverted toward others. My natural way of dealing with things is through introverted thinking, so that means that I do analyze and try to find the connections between different concepts, let this be the concrete concepts in the real world or ideas in my head. But with other people, I am just as likely to use extroverted intuition and see the possibilities, and sometimes it is like it is harder to use introverted thinking when other people are present. Actually, when I know people very well, I can always find new ideas for what to do. On the other hand, if I don't know them much, then I go into sort of Ti-Fe loop, where I analyze everything and try to harmonize with the group. I prefer the first to second.
Or another example, and ISFP that I know. This person uses the introverted feeling as their primary function, and I can see how he constantly thinks about what is wrong with the world and how to fix it. But when we are together, he is much more likely to invite me to more sensory things, like he would make sure that I am well fed and satisfied and he would get me to listen to music and so on, which is more the domain of the extroverted sensation. Not sure what is happening in his head though.
Or maybe let us take the hypothetical case of an ENFJ. To this person it would be natural to have a good grasp on the outside social system, but when dealing with other people, they would be much more likely to attempt to do it by introverted intuition. I really want to have a phenomenological interview about a social situation with a person like that once, because I can not imagine how would something like that even be done inside the head.
So in this way, maybe they are right that we can all be sometimes introverted and sometimes extroverted. But I still think it is a valid information to know, which one is each person. Because there are differences based on this.