There's at least a couple of different components to consider in looking at the concept of "free speech." There's the legal, political component, as mentioned in the First Amendment to America's Constitution. And there's the ethical and moral component. How does free speech apply in private lives and personal spaces, places that the government isn't a part of (ideally)?
I cannot speak to what America's Founding Father's specifically intended with the First Amendment, nor am I a lawyer who's up on the Supreme Court decisions regarding free speech. So, let me first say what I think a legal right to free speech, as it relates to the government, should be all about, and then I'll get to the ethical component in our private lives.
Any government that is meant to be a government for the benefit of the people, rather than the benefit of the government itself, should support a legal right to free speech. Governments are creations of humans, and as such will make mistakes in policy from time to time. A good government (by which I mean both an effective government, and one with the best interests of it's citizens in mind) would be willing to admit when mistakes have happened, and seek to correct them if possible. Free speech allows the citizens to criticize the government, to say when it thinks the government is wrong. It allows the citizens to lobby for change, and to express discontent with the way the government is doing things.
On the other hand, if the government only cares about it's own power, such as a tyrannical government, then free speech is something to suppress. The more citizens are allowed to criticize and express discontent, the more that discontent is likely to spread. When discontent spreads, there's a greater likelihood of revolts starting. That's not something a tyrant wants. A tyranny needs to control what is said, and when it's said, as much as possible if it wants to retain power.
That's what legal rights to free speech are about at a base level: power. In a government where the power is supposed to, in principle, rest with the people, then free speech is a means to keep the power in the hands of those people. In a tyranny, limiting speech, or even controlling speech, is a means to keep power in the hands of the government.
Now, when considering free speech in our personal lives, we need to consider speech in our home, in our emails, on our Facebook walls, on blog post comments, etc. Pretty much anywhere that isn't strictly a case of speaking in relation to the government, really. However, we don't need to necessarily consider them all separately. It should be possible to come to a general understanding of free speech that can be applied to the specifics of each of these different areas. And let me point out, I'm not speaking legally at this point, but ethically.
People should be free to express their opinions, generally speaking, but not if that opinion expressing is going to cause actual harm to others. Note that I said harm, not hurt. It can be difficult if not impossible to avoid occasionally hurting people, and at times may even be necessary for the long term benefit of the one being hurt. For example, if someone is being lazy, and you tell them such, they may be hurt or offended, but if telling them that gets them up and doing positive things, then it was a good thing that you told them. Of course, there are often ways that we can say even hurtful things in less hurtful ways, in an effort to achieve the good benefits we aim for, while minimizing the hurt or offense.
Being free to express our opinions gives benefits similar to those that we get when free to express opinions on the government. We can criticize each other in ways that allow an opportunity to change course, if needed, or perhaps for the other to argue why the criticism is unwarranted. This is, ideally, beneficial to the person being criticized -- or, if unwarranted, to the criticizer when it's explained to them why the criticism is unwarranted.
Now, sometimes I've seen people get called out on the use of certain language on people's blogs, or on personal Facebook pages. All to often, those who are called out will fall back on the "I have free speech" argument. But do you? If you're on privately controlled internet space, can you claim the right to say whatever you want, without consequences, such as blocking or banning?
No, I don't think you can. For one thing, there's the harm issue. Much of what people want to say under the guise of free speech is actually abusive or harassing, such as death threats, rape threats, abusive insults (constantly calling someone a cunt is going to be abusive), and so on. Free speech is important, yes, even in our personal lives, however, it's importance comes from the ability to freely exchange ideas and criticisms in a manner that allows for people to actually consider those ideas and criticisms, with an eye toward improvement for everyone involved. Calling someone names, hurling insults, being abusive, harassing people, etc does not fall under the umbrella of idea exchange and criticism with an eye toward improvement.
Sure, you could claim that name calling and insult hurling are forms of criticism, but they don't function to improve anyone involved. They do function to get people angry, which generally doesn't help them take in the criticism in a constructive manner. They also function to silence people, to make them reluctant to speak up when they see something they disagree with. And if they aren't speaking up when they disagree, then how is anyone going to be able to respond to that disagreement, and argue that they're wrong? Or, on the flip side, what if this insulted and reluctant to speak up person is actually right, but doesn't speak up because of the verbal insults they received in the past? Then those they would disagree with go on their merry way, being wrong. Do you want to be wrong, when you could be right?
But let me back up for a bit, and look some more at the idea of personal spaces, such as homes, blogs, or Facebook pages, and consider if limits can be placed there, even if the speech being limited would be constructive. Legally speaking, the law of America recognizes that the right to free speech is referencing citizens relationship to the government, and not the relationships of citizens to other, non-government related, citizens. But again, I'm not speaking to the legality issues right now, but to ethical and moral issues.
When we're in a person's home, that person has the right to limit the behavior that can occur within that home. This might mean no smoking in the house, or drinking, or drugs, etc. If we violate those standards, they are well within their rights to revoke our invitation. Personal Facebook pages, blogs, and other such sites are analogous to our homes. They're a private space that we have a right to control, including the right to limit people's speech to the non-abusive, non-harassing, non-hateful kind. Those who aren't willing to abide by such rules can certainly have their invitation (implied or otherwise) revoked by means of blocking or banning. Doing this helps to ensure that there is a safe space for people to talk about what might be difficult, triggering subjects, such as discussions of abuse. It also creates a space that is more conducive to constructive criticism that can actually spark some thought.
It may be that there are also limits to the control that one can exert over their personal space, but that's a subject for a different post.