Earlier this year, I noticed something in China that really surprised me. I realized I felt more comfortable discussing controversial ideas in Beijing than in San Francisco. I didn’t feel completely comfortable—this was China, after all—just more comfortable than at home.
That showed me just how bad things have become, and how much things have changed since I first got started here in 2005.
It seems easier to accidentally speak heresies in San Francisco every year. Debating a controversial idea, even if you 95% agree with the consensus side, seems ill-advised.
This will be very bad for startups in the Bay Area.
Restricting speech leads to restricting ideas and therefore restricted innovation—the most successful societies have generally been the most open ones. Usually mainstream ideas are right and heterodox ideas are wrong, but the true and unpopular ideas are what drive the world forward. Also, smart people tend to have an allergic reaction to the restriction of ideas, and I’m now seeing many of the smartest people I know move elsewhere.
It is bad for all of us when people can’t say that the world is a sphere, that evolution is real, or that the sun is at the center of the solar system.
More recently, I’ve seen credible people working on ideas like pharmaceuticals for intelligence augmentation, genetic engineering, and radical life extension leave San Francisco because they found the reaction to their work to be so toxic. “If people live a lot longer it will be disastrous for the environment, so people working on this must be really unethical” was a memorable quote I heard this year.
To get the really good ideas, we need to tolerate really bad and wacky ideas too. In addition to the work Newton is best known for, he also studied alchemy (the British authorities banned work on this because they feared the devaluation of gold) and considered himself to be someone specially chosen by the almighty for the task of decoding Biblical scripture.
You can’t tell which seemingly wacky ideas are going to turn out to be right, and nearly all ideas that turn out to be great breakthroughs start out sounding like terrible ideas. So if you want a culture that innovates, you can’t have a culture where you allow the concept of heresy—if you allow the concept at all, it tends to spread. When we move from strenuous debate about ideas to casting the people behind the ideas as heretics, we gradually stop debate on all controversial ideas.
This is uncomfortable, but it’s possible we have to allow people to say disparaging things about gay people if we want them to be able to say novel things about physics.  Of course we can and should say that ideas are mistaken, but we can’t just call the person a heretic. We need to debate the actual idea.
Political correctness often comes from a good place—I think we should all be willing to make accommodations to treat others well. But too often it ends up being used as a club for something orthogonal to protecting actual victims. The best ideas are barely possible to express at all, and if you’re constantly thinking about how everything you say might be misinterpreted, you won’t let the best ideas get past the fragment stage.
I don’t know who Satoshi is, but I’m skeptical that he, she, or they would have been able to come up with the idea for bitcoin immersed in the current culture of San Francisco—it would have seemed too crazy and too dangerous, with too many ways to go wrong. If SpaceX started in San Francisco in 2017, I assume they would have been attacked for focusing on problems of the 1%, or for doing something the government had already decided was too hard. I can picture Galileo looking up at the sky and whispering “E pur si muove” here today.
Followup: A Clarification
 I am less worried that letting some people on the internet say things like “gay people are evil” is going to convince reasonable people that such a statement is true than I fear losing the opposite—we needed people to be free to say "gay people are ok" to make the progress we've made, even though it was not a generally acceptable thought several decades ago.
In fact, the only ideas I’m afraid of letting people say are the ones that I think may be true and that I don’t like. But I accept that censorship is not going to make the world be the way I wish it were.