[NateDad]

Argumentative generally means arguing without and real reason to do so. Obviously, yes, you should stand behind your position, preferably with facts to back you up. But that doesn't mean you have to go out of your way to start an argument, or be rude while doing so.

There's a big difference between a disagreement and an argument.

[Bartweiss]

This is a crucial distinction. Disagreeing with someone is valuable. Being argumentative isn't about accuracy, it's about ego and self-assertion. If the person you're talking to can't be persuaded, the solution is to call on sources (or if they aren't available, as in an interview, table the topic until they are.)