NOT A TYPOLOGY EXPERT WHATSOEVER, BUT: I think Ni is a driving force for the INTP, but I don't believe it surpasses Ti, the dominant function. Perhaps we unknowingly develop or even mimic Ni when Ti builds multiple frameworks, eventually training our own mind to see relating connections and parts even unconsciously. I imagine that when Ti has exercised many branches of thought, that the brain can unconsciously recognize patterns that are similar to it from the use of Si. The combination of Ti and Si working together would act much like Ni, for excessive use of Ti and Si in this pattern would allow some people to see patterns and possibilities quicker than most, for Ti would already have the background information stored in branches and Si would unconsciously compare previous outcomes of Ti networks and their formation to form a prediction for the future. So could it be that the INTP just uses pseudo-Ni?