There are many arguments to be made in favor of freedom of speech. John Stewart Mill’s On Liberty is the classic presentation. But to my mind one argument stands above all others: The most dangerous ideas in any society are the ruling ideas, the ideas that everyone believes, the ideas that the ruling class promotes. And why are they the most dangerous? Because they have power of the ruling class behind them.
Marx: The ruling ideas are the ideas of the ruling class.
The ruling ideas are the ideas that serve the interests of the ruling class, or at least don’t conflict with them. Some ruling ideas may be benign or even beneficial. But some are guaranteed to be deadly: war, imperialism, capitalism, law and order.
And what are the least dangerous ideas in any society? The ideas that are marginal, despised, condemned; the ideas that don’t have the ruling class behind them. And why are they the least dangerous? Because they have little power.
Some of these ideas will be truly obnoxious: racism, neo-Nazism. Some will be benign. Some will be the hope of humanity: democracy, equality, socialism.
Of these two categories of ideas, which will be quashed when free speech is denied? What kind of speech will ruling power suppress?
Answer: the least dangerous.
The ruling class will never allow its own ideas to be attacked. The ruling ideas are the most protected ideas. And among these are the most dangerous and deadly.