for me, this goes hand in hand with getting closer to the truth: the most trustworthy explanations are the ones that would break at the slightest sign of being incorrect, and are given as many opportunities to do so - it also helps if i make sure there are those who'd be invested in breaking it (thus finding someone to argue about it with). i suppose this makes me seem quite fickle, as it makes the road from devil advocacy to advocacy is a very short one.
essentially, i trust fragility.
what if the overarching principle isn't the answer to why we argue, but rather, the simple fact we do so?
think about it: you can be a crafter to make your own tools, you can be a crafter to make a living and feed your family, you can be a crafter to compete against others of your trade and show off, you can be a crafter for the innovation opportunities, you can be a crafter for the zen like experience of it.... but in all of those cases, the main reason you became a crafter isn't any of those - you became a crafter because you were good with your hands. it sounds shallow compared to all the other reasons, but its essential to our nature - humans use their strengths, skills and talents like a peacock uses it's tail. the justifications and choice to keep doing it come later.
maybe we simply find reasons to do it because.. we're good at it.