I do this to my best friend constantly, but not intentionally. I'll argue two positions at the same time, and he never, ever sees the division. How I feel about something idealistically and how I feel about something practically are often two very different things.
I can identify with that. I consider myself both idealistic and realistic on some levels -- there are ways that I think something would work best and I would hope that one day they would become true, but I'm extremely realistic as well and know full well where things break down and what the issues involved would be. Most people I discuss things with seem to be connected to one or the other but not both, and they have trouble switching gears with me... they tend to put me in one box or another and then argue accordingly, which is kind of tedious to deal with.
It seems so self-evident when someone's position is based on broken reasoning, so I often just let it hang out there instead of refuting it. It wears on me to try since they then just counter my objection with more illogic. How the fuck are you supposed to reason with someone like that?
That's the problem with rationality: It is only convincing to the rational. Thus it is not effective in all situations, in terms of winning consensus and building a connection.
It's not possible to do on a logical basis. You'd have to resort to emotionalism and socially constructed arguments which isn't fulfilling to an INTP.
It's not fulfilling, but there's some things in life we all have to learn how to do... or else I guess the alternative is just to shut some people out. Typically, though, we have to at least learn to deal with family.
I've learned to see some value in consistency/tradition, as well as sentiment and emotions, so I can tap into that. It's not my instinct, and it's not as fulfilling, but I can at least make connections with SJ types pretty well now. The hardest one is one of my kids -- he's ESFP, and it drives me crazy sometimes to get into a conflict with him, because what I have to offer isn't what he wants and vice versa. I don't know how to operate on his level, to make that connection with him, despite my best efforts.
... anyway, that was off-topic, but whatever.