I am inclined to think maybe our First Amendment Rights are too broad for their own good. The most important freedom of speech is freedom to speak about matters not concerning freedom of speech. It is offensive to argue against such freedom of speech, and so it is not unreasonable on the face of it to believe that such arguments should not be allowed, as allowing such argumentative speech dangerously weakens our guarantees of the most important free speech. Once a paricular type of speech gets banned, it is very difficult to legally argue the inappropriateness of the ban (as is typically necessary to change the ban), since to make a good case that a type of banned speech should not be banned mostly necessitates arguing in a way that is banned. Thus it is incumbent upon a nation that treasures such freedoms of speech to take measures to protect them from bans. Enshrining rights in a constitution or bill of rights is one approach. Another effective way to prevent such bans is to forbid (constitutionally or by statute) people from arguing for them. Hard to get a law passed if you can't argue for it! My proposal is for three new rules:
(1) Speech that isn't about freedom of speech is free speech.
(2) Speech against a type of speech being free is free if and only if the latter speech is not free.
(3) Speech for a type of speech being free is free if and only if the latter speech is free.
What makes me uneasy about this proposal is that I also think (as does our legal system) that threatening speech should not be free. And sometimes people should have the right to not be spoken to. So definitions probably would have to be modified somewhat for this to be a good idea. In particular, the line between threatening speech and non-threatening speech is not always a clear-cut one, and so it scarcely seems appropriate to put people in legal jeopardy for arguing exactly where such a line should be drawn. I thought my idea interesting, though. In particular, it is not at all self-defeating as would be the case if one enacted a law saying that speech against free speech (as opposed to a free speech) is not free (hard to enforce a law that is illegal to be spoken!).
Looking at my justification above, one can see there really is no harm in allowing speech for or against freedom of threatening speech. One doesn't have to be at all threatening to argue for freedom of threatening speech. Usually, though, the most convincing argument for the right to express an opinion A is in fact to argue the reasons why opinion A might be correct and of significance. There's some subtle philosophy underlying the right approach, probably.