Historian and free speech advocate Jacob Mchangama explains how suppressing voices often has the opposite effect. From the crucifixion of Jesus fueling Christianity to Barbra Streisand accidentally amplifying photos of her Malibu mansion, attempts at censorship often strengthen what they aim to silence. Mchangama argues that while free speech can be messy and ugly, it remains essential to preserve its many benefits.

JACOB MCHANGAMA: Very often we see that attempts to restrict speech often risk making a martyr out of those that you want to silence.

Take the Romans and Orthodox Jews who were not happy with the teachings of Jesus. It's fair to say that they did not succeed in silencing Jesus, that his crucifixion was instrumental in creating what became Christianity. In fact, Christianity grew to become a much larger religion than Judaism.

Socrates is another example. Socrates was executed by the otherwise open and tolerant Athenian democracy. Yet he is by many seen as the most eminent philosopher of all time. More than two millennia later, his ideas live on and are taught to all college students around not only this country, but in many places in the world.

In ancient times, this was the martyr effect. Today, in our digital world, we might better know it as the Streisand Effect.

Barbra Streisand. Someone took a photo of her luxurious mansion, I think, in Malibu, and she fought to get it taken off the internet. That just prompted interest and the photo was spread everywhere. Instead of maybe 100 people or 1000 seeing it, millions saw Barbra Streisand's luxurious Malibu mansion.

And this is an effect that we see again and again. Not only are people more interested in prohibited ideas, they may sometimes actually be more likely to believe in them when they're being suppressed. So that's an interesting psychological phenomenon.

So that does not exactly suggest that the idea of banning speech is an effective way of limiting the ideas that you don't like.

We'll never have a perfectly ordered public sphere. Sometimes it will look messy and ugly, but that, I think, is a cost worth having for all the immense benefits that we get from free speech.