except we just assume this about everyone we argue against. it always frightens me to think about the fact that in every argument there are two people who think they are 100% right and at least one of them is wrong, sometimes both. because that means i can't always be as right as i think i am.
I don't know about an argument in that sense of the word, but in an actual debate both sides should be open to new evidence and conclusions should be drawn based on the available verifiable facts. If too few facts are available then more should be gathered before a conclusion is drawn.
Some people just can't help themselves from proving they're the one on the left.