Indeed.

I usually talk about a subject of debate because the subject itself interests me...and perhaps moves me emotionally as well. I certainly don't talk about it in order to get into fights with other people, and I'm rather taken aback when someone else decides they want to fight with me about it.

As you say, Ed, 'Why not just reply, "You could be right", and move on?' Seems like a pretty good way to defuse the situation.

punkfolkrocker - You're right about "the ageing process
manifesting in increasing antagonism & belligerence in many individuals". It's the "crabby old git" syndrome! ;-D Every civilization that ever existed has taken note of it in one way or another. Then you have the "mouthy young jerk" syndrome at the other extreme...one that is easily found in the Comments section under many Youtube videos...even less polite than the "crabby old git", the Mouthy Young Jerk is fond of hurling foul language, demeaning the other person's sexual organs, etc... While the Crabby Old Git is often embittered by a gradual decline in physical abilities and bodily energy, the Mouthy Young Jerk is burdened by an excessive amount of energy with no available outlet. In short: he's probably sexually frustrated and feels powerless. His reaction to that is to seek a momentary (and illusory) sense of power by viciously denigrating other people, and he knows he can do it safely by way of the Internet, so he goes to ridiculous extremes of toxic behaviour. A confrontation between 2 mutually opposed Mouthy Young Jerks can go on almost indefinitely and consume large amounts of bandwidth. So too, a confrontation between 2 mutually opposed Crabby Old Gits. If all these hostile energies could instead be harnessed to provide electrical power to the world, it might cure our dependence on oil!