Electric Universe cosmology
You're either one or the other. You can be ambiverted in temperament. But when it comes to MBTI and the functions, you either lead with an Extroverted function or an Introverted function. One has to take the seat of the dominant. Otherwise your brain wouldn't be able to function properly. You can kind of think of all these functions like preferences. We've all got right hands and left hands, but some of us are right-handed and some of us are left-handed (forget for a second about ambidextrous people because that's where my analogy disintegrates XD). Extroverts lead with an Extroverted function which is supported by an Introverted function.
You can think of Extroverts as right-handed people whose left-hand supports their use of the right-hand. You can think of Introverts as left-handed people whose right hand supports their use of the left hand. But one hand must play the supporting role, and one hand must play the leading role. It is the same with your personality type. Sure we can use both, but your preferred way of thinking is your “go-to”, and everything else just supports that way of thinking.
Here is the structure of every personality type. We’ve all got a Dominant function, an Auxiliary function, a Tertiary function, and an Inferior function. Your Dominant and Auxiliary are strongest, and your Tertiary and Inferior are weakest. Your Inferior is the worst of all and where you’ll usually find most of your problems lie.
Your Dominant function is the leader. Everything else is a servant to it. It is King (or you can call it Queen if you prefer, haha). It can overrule any other function. So if you are Extroverted, your Dominant function will be Extroverted. You will always see things first and foremost objectively. If you are Introverted, your Dominant will be Introverted and you will always see things first and foremost subjectively.
Your Auxiliary function supports the Dominant. You can think of it as the “royal advisor”. This function usually helps “organize” or bring to mind other perspectives with whatever your Dominant has brought to the table. However, your Auxiliary function holds nowhere near the power your Dominant does. So if you are Extroverted, your Auxiliary function is always Introverted. But it is a slave to the Dominant. Same goes for Introverts. Usually you really start developing your Auxiliary function around middle school-ish, I notice. Often Extroverts start self-reflecting more and becoming more internally aware, and Introverts become more aware of the External world. Your personality gains a bit more balance.
Your Tertiary function is just much less used. Since you don’t use it a lot, not near as much as you lean on your Dominant and Auxiliary, it hasn’t had as much practice. It’s much less mature. Your use of it is much more clumsy and you’re usually pretty aware that you’ve got problems in this area. Usually you really start developing your tertiary function in your later teens or early adulthood. If you are Extroverted, this function will also be Extroverted, but it usually kind of clashes in some ways with your Auxiliary function. Same goes for the Introverts.
Your Inferior function is the worst of all. It is immature and worst of all, it is totally unconscious. You project the bad stuff of your inferior function onto other people. Often the stuff that annoys you most in others is the very thing you’re awful at. It brings up the concept of “You are your own worst enemy”. Every once in a while when you’re stressed, your Inferior function will try and fight your Dominant for the King position. It’s an all out civil war, really. And since you pretty much NEVER use your Inferior function to the extent you rely on the others, you use it in painfully ridiculous ways and manage to have some serious out-of-character moments. You become that person you really don’t like. If you are an Extrovert, your Inferior function will be Introverted. Which means when you’re stressed, you will begin thinking a way that is TOTALLY foreign to you. Same goes for Introverts. Your brain becomes one confused mentally unstable place. When this “civil war” occurs (usually during stress), it is called being in the grip of your Inferior function. Usually, your Inferior just kind of lurks beneath your unconscious. But every once in a while, it will come up to the surface and you’ll wonder, “Holy cow, where did THAT come from?”
I actually really like the way you describe the inferior function.*facepalm* I was talking with friends over Facebook about personality theory... x_x