Those who would rule know one thing for certain: Win the battle of ideas and you win control of everything. In an open, democratic society such as ours, freedom of speech and what John Stuart Mill called "the marketplace of ideas" are huge benefits. They enable all of us, even the most marginalized, to make our case to the public, to be heard. They allow reason to be inserted into public debate as an essential part of the checks and balances of the democratic process. This is a healthy thing, vital for our republic. But for those who...