A conclusion is only correct given that the assumptions are correct. I'm never 100% certain that the assumptions are correct. However I am 100% that the conclusions are correct if the assumptions are correct.Does Ti "feel" the conclusions it reaches are "right" the way Fi does? (Feel may not be the best word choice)
If you reach a logical conclusion does it "feel" correct?
What input is required to change the answer?
What time frame is involved in changing the answer?
Ti makes me love Truth, but at the same time I think that ultimate truth is ultimately unknowable. Instead I have degrees of certainty. I think this might be what makes me as an ENTP different from an INTP. I don't have one big framework that tries to fit everything together. Instead Ne creates a lot of different scenarios and Ti determines how each scenario will turn out.
Everything I believe is just my best guess, but Ti works out the conclusions to different scenarios based on these guesses. Sometimes I "feel" my best guess has 99% certainty of being true, and other times I might only think it has a 55% certainty. As I get new information I'm constantly reevaluating how much certainty I have to each assumption. If I become confident in a new assumption then I start believing scenario B is true rather than the old scenario A, but scenario B is often worked out to some degree beforehand by Ti.
With Ti I really don't "feel" anything is correct. It's just my best guess. But the "best guess" with Ti is more accurate than the "sure thing" of the other functions.