Probably. Anyway, here it is:
Any function in the MBTI demands an "equal and opposite reaction". If your first function is extroverted, your last will be introverted. If your second function is feeling, your third will be thinking.
Just earlier today, I think I found the reason for why this is. I really can't explain it in abstract terms at the moment. I'll have to give specific examples of how functions negate each other.
Consider introverted intuition and extroverted sensing. Introverted intuition demands an extroverted sensing counterpart because extroverted sensing is an expression of introverted intuition--to be able to act on the world in a way that brings about immediate results (Se), you need to know how the world works as a process (Ni). And if you know how the world works as a process, your actions will reflect that. At the same time, they're opposite functions--to act on the world is to disrupt the process and prevent yourself from understanding it.
This sort of pattern applies for all of the other functions as well. Extroverted intuition demands an introverted sensing counterpart because introverted sensing roots extroverted intuition. I'm not sure how this one works yet (and it's my own type!)--I'll come back to it. My guess right now is that you need at least a basic understanding of "moments in time" (Si) to be able to build ideas off of them. And if you are trying to understand the "moment in time", then you will need things to relate it to (this would be using Ne). Si and Ne are very obviously opposites--to follow potentials which stem from the moment is to disrupt the stability of the moment.
Introverted feeling demands extroverted thinking because plan-making (Te) is a way of acting out individual truths (Fi). And extroverted thinking demands introverted feeling because its plans need ideals to work toward. These are opposites too--to make plans and act is to disrupt the things affecting you which give you self-understanding.
Finally, extroverted feeling demands introverted thinking because the way you "act on the world emotionally" (terrible way of describing it, I know, but Fe) is informed by the models of reality you hold (Ti). And introverted thinking demands extroverted feeling because your models of reality will affect how you act out toward the world. These are opposites because to interact with the world based on your feelings toward it is to disrupt your understanding of how it works.
In fact, they can't match up in any other way (and this is about as abstract as I've gone so far):
Fi and Ti are two ways of building a personalized model of reality--either based on personalized truths or "objective" reality, and you can only have one. Fe and Te are both ways of acting on the world based on an agenda--either by going into the world of "reactions" or by taking action.
Si and Ni are both ways of understanding your place (another variant on model-building)--either as part of an ever-changing process or as parts of a static system. Se and Ne are both ways of playing with this sense of "place"--either by deriving amusement from possible reactions in this system, or by taking action and directing the course of this evolving system.
I feel these thoughts are incomplete. And possibly wrong. What are your thoughts? Please don't tear this apart--I am staking my ego on things like this.