how do you determine whether your partner "can envision anything that will change ones mind on this topic"
You could ask them. I had a long debate with my dad where I eventually came to asking him if he could envision anything that would make him change his mind on religion. It was then that I realized how pointless the discussion had been. Knowing something like this chart beforehand would have saved me plenty of grief.
Unfortunately, that only works if they assume you're asking the question in good faith, which is rare; the standards of casual debate are so low that most people encountering a similar question are going to interpret it as an attack on their conviction, not as a prerequisite for discussion. In other words, "no, I can't imagine anything that'd change my mind" probably doesn't mean what it says on the box, but rather something along the lines of "I'm confident in my opinion; I don't consider myself a seeker or a lapsed adherent, and I'm not t...
I have a feeling that most of the people reading this site already understand everything in this article, but it's a useful synopsis of common issues faced when trying to have a reasonable discussion with laypeople, and might be good to point them to if necessary.
http://thoughtcatalog.com/2011/how-to-have-a-rational-discussion/
I also want to mention how much I wish someone had shown me something like this as a teenager- I was very prone to lecture others against their will- as it might have saved me a lot of grief. I'm curious to see if these tendencies might have been common among members of this community growing up, so please comment to tell me if so (actually, please tell me even if not-no reason to encourage my own confirmation bias)!