Others have said it so much better than I ever could:
“He who knows only his own side of the case, knows little of that…Nor is it enough that he should hear the arguments of adversaries from his own teachers, presented as they state them, and accompanied by what they offer as refutations. That is not the way to do justice to the arguments, or bring them into real contact with his own mind. He must be able to hear them from persons who actually believe them; who defend them in earnest, and do their very utmost for them. He must know them in their most plausible and persuasive form…” John Stuart Mill, On Liberty
“The problem with free speech is that it’s hard, and self-censorship is the path of least resistance. But once you learn to keep yourself from voicing unwelcome thoughts, you forget how to think them – how to think freely at all – and ideas perish at conception.” George Packer, Mute Button /The New Yorker. April 13, 2015.
“Enlightenment is man's emergence from his self-incurred immaturity. Immaturity is the inability to use one's own understanding without the guidance of another…For enlightenment of this kind, all that is needed is freedom. And the freedom in question is the most innocuous form of all freedom: to make public use of one's reason in all matters.” Immanuel Kant, An Answer to the Question: "What is Enlightenment?"
This post was inspired by reading The Next Word by John Seabrook in The New Yorker. In this piece, Seabrook refers to the work of linguists Linda Flower and RJ Hayes, who developed a cognitive process theory of writing. In brief: insights derived from the work of putting together words continually undermine the writer’s initial and ongoing assumptions. In other words, the act of writing is a disruptive learning process, the more so when the writer approaches her task in the spirit of openness to where the words may take her. Like writing, speech is an act that sets in motion unpredictable feedback loops and by so doing, gets us closer to the truth of things.