Under a doctrine of free speech, politics has no "clearly false messages". There are only "messages". You are, however, allowed to state that a message is "clearly false".
Thus if you wish to say that the world is flat, then you are allowed to say so, and others are allowed to state their supporting or opposing arguments on the same topic on the same forum, and everyone is allowed to listen.
Under a doctrine of free speech, politics has no "clearly false messages".
Free speech and the correctness of a message are orthogonal concerns - the Earth is flat is a false claim no matter whether there is free speech or not and neither supporting nor opposing arguments have any bearing on that fact, they may however influence other people accepting or rejecting it.
Free speech (a la First Amendment) has limits. Case in point: the FTC and deceptive advertising; The courts have repeatedly held that deception is not protected speech.
A good way of looking at rights is: yours end when it begins harming someone else. For example, one can “assemble”[^a] and protest, but once you start getting violent, your right to protest is gone and you’ll probably be arrested.
Tangent:
However, there is a controversial reading of the concept of free speech (concept, not First Amendment), and that is: what about monopolies silencing you? Most people would agree that removing a disorderly person from your restaurant is ok, but where do you draw the line when it comes to monopolies?
As in, what if a restaurant chain owned 90% of the restaurants (all brands included) in the country, and they banned you because they didn’t like the words coming out of your mouth?
I don’t know the answer to that.
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[^a]: quotes because the First Amendment refers to it as “assembling”
“Yours end when it begins harming someone else” is in itself a slippery slope and a dangerous precedent used by folks to limit free expression. How exactly do you define “harm”? Does emotional or mental or spiritual/religious harm count? If so you are one step closer to a complete dismantle of the first amendment.
Hence I think that statement should be extremely narrowly applied to direct physical violence (and threat of), and that’s it. Anything more and you are just masquerading as wanting to censor speech under the guise of that highly exploitable statement.
It’s for sure a slippery slope, but it seems to be the way the courts have ruled. Thankfully, they’ve generally taken it case by case (except for the Miller Test), and (generally) rejected the concept of “prior restraint”. It’s why I said it’s a good rule of thumb, not an absolute.
> Does emotional or mental or spiritual/religious harm count?
Actually, it depends. Sometimes yes; sometimes no. Anti-bullying laws are very much a thing, but then there’s the Westboro Baptist Church (where the courts have ruled their hate speech is protected).
Wikipedia has a list of “free speech exceptions”[0]. Among those include fraud (sometimes in the form of depriving someone of property through lies), CP (harm to minors), threatening the President, and others.
I think the argument is that political arguments are rarely of the "The sky is blue" category, but more along the lines of (and I'm making up an example here). "The economy has never been better"
There are several ways you could measure this - is it based on the S&P Index? Rising GDP? Income inequality reducing? Low unemployment? Balance of Payments? Not all of those measures may be true at once, and if they're not true which one is the correct measure?
The relative importance could vary from person to person. Somebody with, say, a large pension fund might see the S&P Index as the most important measure. Somebody else might view it as income inequality.
You could argue a case for each one, and each voter would have to make up their own mind as to whether they agree with the statement.
Thus if you wish to say that the world is flat, then you are allowed to say so, and others are allowed to state their supporting or opposing arguments on the same topic on the same forum, and everyone is allowed to listen.