Another way of putting it is that those whom one is trying to convince often hold their own opinions in very high esteem, regardless of the facts of the matter.
It also serves to explain how INTJs are often perceived as arrogant: how can we speak with such authority when we have not first established our legitimacy? INTJs have the opposite perspective: we base "legitimacy" on whether someone makes sense in the first place.
The problem isn't "half-ass" arguments, per se: it's that any argument that Ti doesn't immediately understand sounds half-assed. Note that the bolded portion is where the conflict with Te begins: any Te-style argument is looking for reasonable counterarguments (though immature people will still try to "win" such exchanges). The refusal to give a counterargument sounds like stubbornness, like intransigence. What's really going on is that Ti has a hard time pinpointing logical flaws: an incorrect argument sounds 100% incorrect, even if the "flaw" is a simple misunderstanding, e.g., one person having misheard a word or holding a slightly different, but valid, definition.
Te, on the other hand can be rather adept at finding communication errors, missing information, extraneous misleading facts, and so on.
What if it doesn't "add up" but it sounds fair and reasonable?Agreed. I don’t care how many letters someone has behind their name: if what they’re saying doesn’t add up, then I won't go along with it.
On the Te/Fi side of things, the attitude seems to be one of giving the benefit of the doubt until one proves oneself to be stupid or incompetent, while on the Fe/Ti side, the attitude appears to be one of distrusting one's competency until it's been proven. Does this conform with others' perceptions of the matter?
Oh, and I almost forgot:
*gives Domino a doughnut*