I disapprove of what you say, but I will defend to the death your right to say it." -Voltaire
Sometimes, I'm surprised when I realize that a lot of people don't believe in free speech. I guess I shouldn't, really, since the concept is only a few centuries old, compared to millenia of human history.
The incident that really brought it to my attention was a couple months ago. A professor here at Purdue posted an argument against gay marriage on his personal blog. The argument he made was frankly, pretty stupid. But I won't get into that, since plenty of other bloggers have taken care of that for me, and it's really not pertinent.
This was a rather large controversy then, there were many letters to the editor in the Exponent, and other blogs talking about it and such like. What struck me is that so many of those who disagreed with him wanted him to be fired from his position, or otherwise disciplined. When others pointed out the whole freedom of speech thing, the response was that the constitution's guarantee of freedom of speech didn't apply in this situation. That's true, the constitution doesn't forbid an employer from firing an employee for saying the wrong thing.
But that's not the point. When I talk about free speech, I'm not referring to the constitution. I'm talking about the principle. And the principle is that you don't want someone punished just for saying something that you disagree with. Even if it's wrong. Even if it's bigoted.
The whole point of freedom of speech is that it's the only way to determine whether something is wrong or bigoted. Just because people think something is wrong, doesn't mean it actually is. The only way for new ideas to be accepted or rejected is for the ideas to be expressed and critically examined. The appropriate response to someone saying something you disagree with, no matter how strongly, is not to call for their punishment, but to explain why you think they're wrong.
That was the biggest incident, but since then I've noticed other similar examples. Even though free speech is one of the things the modern world was founded on, it seems it hasn't really sunk in yet.