Then who do you propose be the arbiter of who can comment and on what topics?
Are we back to on-line discussions again now? If so, then I haven't proposed any general limitation on who may comment, only that when doing so people shouldn't be able to claim protected qualification or authority that they do not legitimately possess.
To me, that is still a restriction on absolute freedom of speech, but a justifiable one. I see no general need to protect malicious liars from the harmful consequences of their actions under colour of defending free speech. Others here seem to feel this isn't a freedom of speech issue but more a matter of fraud, which to me just seems like quibbling over semantics, but maybe their views and mine aren't so different after all and we just frame the argument in slightly different ways. Perhaps protecting speech yet punishing its consequences is a particularly US way of looking at the issue, like framing the debate in terms of the First Amendment rather than any specific moral, ethical or practical motivation?
How do you propose that the system does not become corrupt like our allegedly free democracies?
The qualifications are awarded by peers through an open, transparent process. As I commented elsewhere, that is the best system I know of for recognising any particular qualification or authority. It's not perfect, but to defeat it you have to corrupt the entire expert body in a field, and if you can do that then the field has no value anyway.
If you claim to want control, there must be a controlling entity.
But that controlling entity doesn't have to be part of the government, any more than we have courts that make determinations of guilt or innocence based on the whim of the Powers That Be rather than people being tried by juries of their peers.
Censorship can not be implemented without corruption, and though repeatedly attempted in history it has _ONLY_ resulted in damage to society. Never has censorship been implemented in a positive way, because it can't be implemented in a positive way.
I'm not so sure. Censorship is a very dangerous thing, and if you said that free speech should only be obstructed when it is necessary to protect other fundamental principles, I'd be the first to agree.
But I don't accept your premise that anything resembling censorship is automatically a bad thing in any context. People lie, with damaging consequence. Even when they aren't lying, you can't force people to tell the whole truth, and a half-truth may be worse than saying nothing at all. You also can't give everyone the power to speak with an equal voice, but otherwise reasonable arguments about defeating negative speech by countering rationally with a more positive alternative tend to assume a right to reply exists, which of course it doesn't in practice. Unless you're going to physically compel everyone to provide such a right of reply, which you can't because it's completely impractical, you have only traded one form of censorship for another anyway.
Consider those things in the context of, say, modern political systems, and you can immediately explain much of the corruption we see in the world today. Consider them in the context of a specialised profession like medicine, and you can immediately explain a lot of problems in the US healthcare industry.