So how do you encourage an arena that allows for vigorous debate and sharing of ideas, without it degenerating into personal attacks and petty insults?
It's not that complicated. We're all human. We all say foolish, sometimes hurtful things without thinking them through (and sometimes we're annoyed enough to do it deliberately). We all have cultural blind spots, where ingrained habits may have problematic origins or consequences. We all mistakenly transfer habits and modes of interaction from one context to another, even when that may not be appropriate. We'll say things we don't mean because we're stressed about work, or an ill family member, or our pet just died. It happens, it's going to keep happening. We'll make other people angry, they'll make us angry.
We need to accept this (human nature: a thing), and we need to learn to adopt the many and varied techniques that have been invented to manage it.
We can set up safe spaces, where we suggest to people "only come here when you're able to interact in a calm, controlled manner". Not every space needs to be a safe space for everyone - the behaviour that's appropriate for a professional conference is going to be starkly different from that of an evening drinking and playing cards with your closest friends. What's entirely appropriate on a personal blog may be completely out of line on a shared collaborative mailing list.
We can create spaces to vent - to shout into the wilderness, whether anyone is listening or not.
The internet is, above all, a very human place. It allows us to connect, if ever so tenuously, across geographic and cultural boundaries that may have previously seemed insurmountable. We can, if we so choose, create a "filter bubble" where we only ever hear opinions that already agree with our own. But that's a choice - it's up to us. If we want, we can instead, dip into the cacophony, welcome the noise, and perhaps learn a little bit more of the invisible worlds that exist in parallel with our own every day, across the world, across town, and even across the street.
And if that means I have to get a little better at the arts of "agreeing to disagree" and even (gasp) "admitting I was wrong"? I'm still in :)