When you encounter someone with whom you disagree directly - a "yes it is/no it isn't" type of disagreement - please try something other than head-butting for resolution. If your first response to a conversation that started with "Yes it is", "No it isn't" is to say "Yes it is" more loudly, the next response is not going to be "Oh, I'm so sorry, I didn't realise, but your loudness must indicate the force of your belief and therefore your correctness. I humbly apologise." Like five-year-olds who lack negotiation and proper argument skills, you're just getting into a yelling match. If you recall being in that kind of conflict at age 5, it ends when someone hits the other or backs down in tears.
There needs to be some substance to your argument. Try "Oh, I thought such-and-such meant that this was the case." At least that offers the possibility of debate rather than the suggestion that you are digging in your heels and stubbornly refusing to be swayed on an opinion you have pre-decided.
Mokalus of Borg
PS - Sometimes I get sucked into a content-free disagreement.
PPS - It's hardest to step out of it when I'm tired.