Okay so your solution is to give as much room as phrenology wants. If it gets incredibly popular then so be it, let the masses think that certain races are less intelligent due to head sizes.
Phrenology already had its chance, man. Look, the apocalypse didn’t happen.
You think you’re smart enough to determine which ideas should be allowed? How do you know you won’t be the Church burning Galileo at the stake? Hint: you don’t know that. That’s why you have some humility. Ultimately ideas that don’t work will fail.
Enlighten me. Please do describe the concerted efforts by governments and institutions to ban discussion of phrenology. What was the punishment for unauthorized phrenology lectures? Are you not violating all these anti-phrenology laws right now by even bringing it up?
> The ban seemed to make phrenology more popular, and it spread to other European countries.
Literally the very next sentence. Banning things doesn’t work.
Phrenology died out because it was openly discussed, debated, and debunked. If you are confident you can prove you’re right about an issue, you don’t need to ban anything, you just go ahead and prove that you’re right. When you start banning things people only take that as evidence that it’s some secret forbidden knowledge that threatens the existing power structure and they’re even more motivated to pursue it.
Who could that possibly hurt.