What exactly is this behaviour called?
When someone repeats an argument that has been proven false /badly argued many times before, but keeps repeating it in hopes of drowning out opposition or derailing a thread. Yet not disruptive enough to get banned on forums, as it wraps itself in non-hostile, nicely written sentences.
How exactly do moderators deal with this kind of behaviour?
it's called arguing in bad faith, or more specifically argument ad nauseum
ad nauseum
Thanks, this is an exact description.
Small nitpick: It is spelled ad nauseam.
In politics it's been called "flooding the zone"
Could also qualify as "sandbagging" or simply "bad faith"
Repeatedly using a blatantly false assertion is called the Big Lie (https://en.wikipedia.org/wiki/Big_lie). The derailing/zone flooding aspect, as @NOT_RICK@lemmy.world stated, is a Gish Gallop (https://en.wikipedia.org/wiki/Gish_gallop). There might be a term for using these together, but I am not aware of of what it might be.
Neither of these really apply?
The big lie refers to a very big lie, but OP is talking about something subtle.
A gish gallop refers to many lies, such that an opponent cant refute all of them, but OP is talking about one lie.
I think this is just a form of propaganda. If you really want a name then maybe Ad Nauseum.
Tricky to moderate. You need to identify, and have objective evidence of, a pattern of behaviour from a user. It needs to be enough that an independent ambivalent third party would agree that the intent is propaganda. I think this is kinda impossible honestly.
If its a small fiefdom community, just ban them.
Gish galloping I think? If they're repeatedly asking you to prove the argument false that falls under sealioning too. It's also a very common tactic for some trolls to pretend to be civil in order to bypass suspicion.
I’ve always referred to it as cognitive dissonance.
Astroturfing?
Unfortunately, it is a split issue, so both sides get some support.
I don't know what you're describing is called, but since the world is measured flat and I, for one, didn't evolve from monkeys, your point is moot. Respectfully.
Well… it might surprise you, considering the context of your comment but you are partly correct: Humans did in fact not evolve from Monkeys.
Sounds like maybe a Gish gallop?
It would be a Gish gallop if they do some brigading; that's how they usually scare off OP. Since he did not know he was making a controversial statement, and did not pre-emptively stop the Gish Gallop.
Being a shithead. Master this "skill" and you can lead nations.
sealioning ?
This one I've always been wary of. I studied philosophy so I know a bit about arguments and sealioning is unusual because it can only really take place over the internet where someone is asking questions in bad faith and you can't 100% call them out because you don't know their identity for sure. Firstly I don't like the idea that questions can be bad faith - especially seemingly trivial or obvious ones - since that goes against the Socratic method of questioning all your beliefs/shibboleths. Secondly, it is so context dependent that I think it is hard to universalise it like you can do with other fallacies like false dilemma (everyone is either a tequila or a whisky person, etc.)
Sea lioning is pretending to be interested in a reasonable discussion when you're really looking to wind someone up until they lose their temper.