Quote Originally Posted by FDG
Because otherwise, where do you get that information from? You have TI for the introverted judgement, Ne for the extraverted perception, Si for the introverted perception, Fe for the extraverted judgement.
Okay, I don't know for sure either way, but I'll play along with this for awhile longer if you will indulge me.

Why do you say that we would need an extraverted and introverted judgement, and an extraverted and introverted perception. Why make whatever distinction you're making on those lines. Why not make on the function, we all need a feeling, a thinking, a sensing and an intuition. For an INTJ that would be Fi Ti Se and Ne. Or, we need all of them. And when dealing with sensing data why are you sure we only use one sensing function. We use both don't we? And one is more repressed.