Its mouseover text: "I can't remember where I heard this, but someone once said that defending a position by citing free speech is sort of the ultimate concession; you're saying that the most compelling thing you can say for your position is that it's not literally illegal to express."
Panel One: This only refers to the legal right of free speech, and it's objectively wrong. Every country can arrest you for what you say. Julian Assange and Edward Snowden will happily assure you that the US government has that power, and the Pirate Party will add that you can be arrested for sharing things corporations claim through copyright, trademark, or patent law. The list of limitations to legal free speech in the US is long—see Wikipedia's United States free speech exceptions.
But the difference between the law and morality matters. I have a legal right to try to silence anyone I want to, but I have a moral obligation to support everyone's right to speak, no matter how much I disagree with them.
ETA: An example of free speech that's legal but generally considered immoral: "outing" people by sharing information they would prefer to keep private.
Panel Two: If anyone can link to anyone who says everyone should have to listen to everyone or host everyone, I'd be grateful. Otherwise, the stickman is arguing with a strawman.
Update: I got email from someone who offered this as a possible example:
I remember when TV networks believed in the First Amendment. http://t.co/IK2fvrqGPnIt's hard to tell too much from a tweet, but Jindal's a Republican, so I think we can safely assume that Jindal believes the marketplace should decide who gets to be on commercial TV. Since Duck Dynasty wasn't canceled, things worked out as Jindal thought they should.
— Gov. Bobby Jindal (@BobbyJindal) December 19, 2013
Panel Three: More strawman.
Panel Four: When you've been invited to speak and then are prevented from speaking, the principle of free speech has been violated, even when it's legal. When Clark University invited Norman Finkelstein to speak, then canceled the speech in response to protesters, Sarah Wunsch of the ACLU wrote:
...the cancellation of his speech violates the basic principles of freedom of speech and academic freedom which are so fundamental to an institute of higher learning. The existence of an opportunity to speak at another time or in another location does not remedy the wrong of censorship.
...Nor may complaints from those disturbed by Finkelstein’s writings about the post-Holocaust “industry” justify a decision to prevent the lecture from taking place. Indeed, even if demonstrators came to protest against Finkelstein’s views, the obligation of a university is to protect the speaker’s right to be heard and prevent disruption of the speech by others. By censoring speech because of complaints about offensiveness or the controversial nature of the speaker, the university has essentially allowed what the courts call a “heckler’s veto” over what speech can be heard.Panel Five: Every censor makes that argument.
Panel Six: And that's every censor's goal.
Mouseover: When you cite free speech, you are only asserting a right to speak. By definition, you cannot convince ideologues you are right, but when they have the power to silence you, you can hope they have enough respect for free speech to let you speak despite their belief you're wrong.
Note: Many fans of censorship think only governments can censor. Not true. From the ACLU’s “What is censorship?”:
Censorship, the suppression of words, images, or ideas that are “offensive,” happens whenever some people succeed in imposing their personal political or moral values on others. Censorship can be carried out by the government as well as private pressure groups. Censorship by the government is unconstitutional.
In contrast, when private individuals or groups organize boycotts against stores that sell magazines of which they disapprove, their actions are protected by the First Amendment, although they can become dangerous in the extreme. Private pressure groups, not the government, promulgated and enforced the infamous Hollywood blacklists during the McCarthy period. But these private censorship campaigns are best countered by groups and individuals speaking out and organizing in defense of the threatened expression.ETA: Turning off comments. I completely agree that no one has an obligation to host discussion they do not want to hear. On free speech, I will always be on Voltaire's side, and I hope I'll always be on the ACLU's side.
ETA 2: It bugged me to turn off the comments, so I turned them back on.
ETA 3: Wikipedia has a nice short article on the Marketplace of ideas.
ETA 4: There are many fine comments on this post, so please skim them before adding another. In particular, I recommend Kasper Brohus Allerslev's long comment, which makes these points, among others:
"Freedom of speech is, at least to me, more an ideal than an actual right."ETA 5: Actually, what XKCD doesn't understand is that money is not speech (XKCD doesn't understand free speech, take 2)
"Taking away a person's right to speak is not the same as not listening."
"We do not want to live in a society where opposition is quelled. We want to live in a society founded on reason. "
"When people go out of their way to punish you for your beliefs, that's an affront to the freedom of speech."
ETA 6: RE: xkcd #1357 free speech | Sealed Abstract
ETA 7: I made a short response in a cartoon: Explaining free speech to XKCD, a cartoon