For me, the difference is between arguing and discussing, and it has nothing to do with the volume of the exchange. Arguing has to do with defending your position of being "right." Discussing has to do with offering your perspective but being open to hearing another person's, even if you don't ultimately change your position. SS, your example of paying taxes is perfect. If your sole purpose is to make your case, then you're not even open to the reasoning behind taxes. You, then, would simply be arguing. But in order to be able to hear the other side and factor it in to your perspective, a discussion is definitely warranted since no one has yet figured out how to read minds. I have had many, many discussions at work. Few would consider them arguments because we all believe we're on the same team. Arguments happen when you position yourself on opposite "sides," not simply opposite perspectives, and don't even allow for another legitimate perspective besides your own.
I'll at least say that for us, we don't have discussions, we have arguments, even though they're not loud either. And the problem in our sitch reflects the quote above exactly.
CV: Today would be a great day for a float trip. H: Today would be a great day to go boating. CV: Yes, it's a great day for both. I'd rather go floating. H: I'd rather go boating. CV: Okay, then you go boating and I'll go floating. H: No, you can't, you need to go boating with me because that's what a family does. CV: Except that I've already gone boating 5 times with you this summer and haven't gone floating in 6 years. H: I know, but ..........
