I don't know that there is one which functions.
Bad actors will try to game every system and must be opposed else they will take over. Passively by setting up the system to resist gaming and ensuring incentives are encouraging the desired behavior. Actively by having people make judgement calls, nudge actors in the right direction, and tweaking the system as the behavior of actors evolve. It's hard, complicated, messy work.
I'll frame this as a reply to Ryan_L's answer about the Free Market of Ideas, how his own example is a demonstration that its failed, the common fallacies of dealing with intolerance, and my own experiences walking the grey area.
The Efficient Market of Ideas
the counter-theory is the free market of ideas
Free as in unregulated.
despicable beliefs will struggle to gain popularity when forced to compete for attention fairly against moderate beliefs.
Their market has a purpose, and they believe it will gravitate there naturally.
Markets don't just exist as a clicker game to make number go up. Whether its goods or ideas, markets exist for their efficient distribution through competition. This doesn't just magically happen, markets can fail. We've been doing markets long enough to know the warning signs of failure. We know what sort of practices lead to failure. We can set market rules to dampen them. We can step in to prevent them when it seems failure is imminent.
We can argue all day about how to do this, but markets must be regulated to ensure they remain efficient which includes the "marketplace of ideas". This is a broad grey area with lots of room for argument, but I hope we can agree that a truly free market with no regulation leads to market failure, and there are measures we can take to prevent failure and keep the market efficient.
This is just the Paradox of Tolerance redone in economic terms. We want an efficient market of ideas, but free markets are corruptible. We need rules and regulators to prevent corruption, but those are also corruptible. Over-regulation is bad. Too little regulation is bad. We need to strike a balance.
The Problem of Money in the Marketplace of Ideas
When Twitter and Youtube banned Alex Jones, he didn't just disappear.
Alex Jones is a great example of perverse market incentives and the problem of money in the marketplace of ideas. Money, and the utility of folks like Alex Jones to people who have money, mean he is not operating in an efficient marketplace of ideas.
Whether you think Alex Jones really believes what he's saying or not, he's making a lot of money saying it. He's turned the attention he's getting into advertising money and political donations which allows him to expand his operations to get more attention to get more money to get more attention. It also allows him to hire expensive lawyers to defend himself.
Companies are incentivized to put their ad money where their potential customers will see them. When companies buy ads from Alex Jones they boost his ideas so more people see them which gets more ad money causing a snowball effect. This has nothing to do with the company supporting his idea, they just want to sell their product.
Political campaigns might see Alex Jones is reaching quite a number of people, a reach boosted by advertising money. They might run their own ads with him, more money. They might even align themselves with him to gain the support of his followers bringing him into the mainstream as we've seen happening in the US.
This is a free market, but it is not an efficient market. The influence of advertising money acts as an anti-democratic boost for ideas. Once an idea gains enough followers it might get a futher boost from a politician or political party who doesn't really believe in their ideas, but wants those votes.
Regulation is necessary to keep the market efficient. On the internet we've largely left this in the hands of private companies, whose own incentives are also muddled by money, who only have so many tools. The result has been a mess with everything from demonetization to lifetime bans applied inconsistently. This is an example of how not to do regulation: piecemeal, conflicted, unprincipled, opaque, ever-changing, and inconsistently applied. This is an example of what happens without regulation, individual actors will start to act in their own best interest. Hosting folks like Alex Jones will anger their customers which will spook their advertisers which will threaten their business. Twitter and YouTube and Facebook are businesses and will begin banning anyone who threatens their business.
This is a consequence of a free and unregulated market of ideas. Saying Twitter and YouTube, businesses who exist to make money, shouldn't ban Alex Jones from making money using their megaphone is advocating for regulation.
Social Media Gamed the Free Market of Ideas
Bemoaning the behavior of big Social Media companies is recognizing that the free market of ideas on the internet has failed. They gamed it to make money.
Here's a quick potted summary.
In the Ye Olde Internet of 2000, we had privately run forums and chat systems for small, niche communities. They could only get so big. They were either self-funded, or maybe had a few banner ads. Twitter and Facebook came along as sites to stay connected with your friends. Google was a search engine. Apple made a slick phone. YouTube was to share videos. None of these had much influence on our lives when they started. None of them had "algorithms" to decide what you saw. You saw what you chose to see.
This was something like a free market of ideas.
As more people came onto the Internet, non-Internet companies took note and advertising money started to roll in. It became in the economic interest of social media companies to keep you locked to the screen for as long as possible to push ads, that's how they make money (and selling your behavior). The companies would influence what you saw to show you what was more likely to keep you watching so they could make advertising money. If their algorithms say that's Alex Jones, they promote Alex Jones. It has nothing to do with the merit of his ideas, just the eyeballs he can capture for ad revenue.
And the free market of ideas was broken.
The backlash over this threatens their ad revenue and employee retention. If they think banning Alex Jones will make them more money than not banning him, they'll ban him.
And the free market of ideas reacted.
This is obviously very simplistic, it's just enough to point out the largely unregulated free market of ideas has already failed and in entirely predictable ways. Market actors are now fighting with the tools available to them according to their incentives.
Big Social Media companies both run the marketplace of ideas, and they are part of the marketplace of ideas. The have an outsized influence over it, and are using it to make money hand over fist. If you don't like this, if you think they should act against the perverse incentives, you are advocating for regulation to make the market more efficient.
Social media companies have become anti-competitive vertically and horizontally. Why do I need a Facebook account to play a VR game? I feel a breakup is necessary to remove the perverse incentives. For example, your power company does not sell below-cost appliances which only work with their plugs, display ads, and ensure you use as much power as possible. They're not allowed to be in the appliance business at all.
Lies Hurt the Market of Ideas
A comment thread on Ryan's answer can be summed up: a free market of ideas sometimes gives you Hitler. This is an important point.
"Ideas" can invoke airy visions of the abstract (mathematical formulas, alternative forms of government) and honest debate. It also includes behavior between consenting adults which others might find objectionable (anything to do with sex and death, for example). It includes ways of thinking about the world and plans for action.
Getting people to repeat and spread your idea gains you believers. Belief can shape how people act. It can bring them together to act in concert. Ideas are power.
"Ideas" also includes lies: communicating with intent to deceive. Dishonest debate. Logical fallacies. Propaganda. Selective editing. Forgeries.
Safety allows broader ideas
It's a lot easier to allow Nazi talk when they're a joke, when it's abstract. Less so when there's a real threat of violence because of those beliefs. If people feel safe and are safe, we can float more ideas because they're just ideas, not threats.
People who believe an idea strongly enough can take action. That could be something innocuous, like a long-winded answer on the internet. ;) When that idea says something is dangerous it might be used to justify strong action. When it's an idea we all agree on like "don't take other people's stuff" that may be justified. When it's an idea founded on lies like "jewish space lasers cause wildfires" now the idea is dangerous, what will people justify in the mistaken idea they're preventing wildfires and saving their homes?
When we talk about The Market of Ideas this is not some academic abstract. The lies affect people, hurt people, and kill people. Harassment and threats push people away from discussions, events, conferences, and public places; those people have ideas who have now been pushed out of the market, not on their merits, but by threats and intimidation.
Ensuring the safety of the participants in the market allows more ideas and lets everyone participate. A nice example is the long running paranormal and conspiracy broadcast Coast to Coast AM which explores fringe ideas while avoiding incendiary racism.
Regulation is messy, and you have to try
Further, banning certain kinds of speech doesn't prevent the thought behind it. The speech will continue, it just won't be where you can police it.
Drawing the line and picking judges seems like the kind of issue that could spark a war, given the current polarization.
Ryan's argument can be reduced to the absurd: we shouldn't make anything illegal because that doesn't make it disappear, it just pushes it underground. There are plenty of cases where laws and regulation had the opposite effect, drugs won the drug war, but we don't give up on laws and regulations as a result. We fix them. Why? Because we know preventing all harm is impossible, but we can reduce it.
Ryan claimed banning Alex Jones was pointless because he'll just go post elsewhere. If it made his ideas stronger, why is it a problem he was banned? Banning him from using Twitter and YouTube's gigantic megaphones has greatly restricted his reach and influence, and that's a good start.
Banning him doesn't prevent the thought, it limits its spread. People are not born with fringe beliefs, they are taught them. And, quite importantly, it also makes it difficult for him to make money.
By the time Alex Jones was banned the damage had already been done. Twitter and YouTube helped make him. They didn't have to. Why was he allowed to use their money-making megaphones for so long? We've covered the perverse incentives. There's also a lack of policy and a lack of tools.
Fighting over regulation enables bad actors
Some of Alex Jones's influence is because he has co-opted the fight over free speech surrounding him. People who would find his ideas reprehensible rush to defend his right to say it. He gains supporters and influence not for his ideas, not even because of the controversy around his ideas, but because of the public fight over what circumstances a multi-billion dollar international corporation will let people use their megaphone so both of them can make money.
The situation was already extremely broken, and it didn't have to be.
Being reactionary is a common mistake in regulating bad behavior. Alex Jones was banned in 2018, long, long after social media companies should have discussed and resolved their policies. Dealing with problematic behavior in groups is not something new. Any number of experienced community moderation experts could have, and tried to, advise the big social media companies and walked them through expected scenarios. Their policies should have been written and tested and adapted as they expanded. Instead any action was resisted until the problem got too big to ignore. They were slapped on and enforced in a reactionary, ad hoc, and opaque fashion.
Which is to say, if you do nothing about a growing problem it's going to be a shit show when you finally address it.
If social media companies had developed principles and policies for behavior as they grew, and applied them consistently, there wouldn't have been a big fight over banning Alex Jones. Those debates would have been worked out long ago and not in the heat of the moment. They would have gained experience in dealing with bad actors and fallout from bans. Any fights would have happened on a smaller scale and the adjustments to avoid them already in place. There would not have been a long, drawn out debate over free speech for him to co-opt. Alex likely would have been banned sooner and would not have been able to use those platforms to build such a large following.
Banning is a tool of last resort
Much of the arguing over tolerance comes down to the issue of banning. Banning is a tool of punishment. Punishment is the last resort and in some ways represents a failure of the system not to rectify it sooner. Having to ban someone is reactionary. Sometimes its necessary, but there are so many other tools in the toolbox to prevent the situation from reaching a ban. Here's a few.
Safety. As mentioned earlier, you can have broader discussions if everyone is safe and feels safe. How you do this will be different from person to person and event to event.
Justice > Equity > Equality. Equality pretends everyone is already equal and should get the same treatment. Equity recognizes we're not equal and need different support. Justice addresses the causes of inequity. Seek to address the root causes of problems, portion out corrections as needed by the participants.
Framing and constraints. There's an idea that everywhere on the internet is a free-for-all, such places are difficult to control. Most places are not; you're there for a purpose. Stack Exchange employs this as a moderation tool; many troublesome areas of conversation can be ended simply because they are off-topic. A PITA meeting is not where you bring up your questionable ideas about race; no debate, it's simply not why were here.
Subdivide. Coming up with a single standard for behavior for 300 million worldwide users discussing anything and everything is tough. Subdivisions allow for different standards of behavior. Expectations at a sex club are different than at a pre-school.
Informed, non-coerced consent. Your participants must know what the rules are, choose to participate without coercion, and be free to leave if they disagree. The network effect of enormous social media companies makes this nigh impossible, it's like saying don't use a phone. Nobody can tell you you must attend a sex club or you'll lose your job.
Clear definitions, actionable rules. A lot of places say "be respectful to others", but what does that mean? Some might think it means to dress a certain way. Some might think it means women should demur to men. Vague rules create conflict. Having to list every way you're not allowed to discriminate might get tiresome, but it is clear.
Observation and conversation. Why are they behaving this way? What's their viewpoint? What are they trying to accomplish? Try to work with them. Maybe they have a misconception that can be corrected. Maybe they're angry about something and don't know how to express it or correct it.
Education. These are the rules. This is how you're violating them. Here's the consequences of violating them. Here's how you can do your thing and not violate them. Education is also getting participants to understand why the rules exist, and why it benefits them to follow them.
Consistency. The rules must be enforced consistently else folks won't have faith in them. Nobody gets a pass because they're too important.
It boils down to this. Dealing with people is as complicated as people are, and the system they're in effects their behavior. A hands-off approach allows bad actors to rise. A simplistic approach marginalizes those who don't fit that simple mold.
Creating a system to encompass human depth and complexity, while offering incentives for good behavior, is hard, continuous work.
