What are the Proper Limits of Free Speech?

Each answer below receives a random book. Apologies to the entrants not included.

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To answer this question one need look no further than John Stuart Mill’s essay On Liberty (1859): “The only purpose for which power can be rightfully exercised over any member of a civilised community, against his will, is to prevent harm to others.” He added that “all silencing of discussion is an assumption of infallibility” — in other words, we can never be sure that the opinion we’re endeavouring to stifle is false. Mill also cautions against ‘the tyranny of the majority’ in imposing their views on a minority, and points out that ages are no more infallible than individuals, every age having held many opinions which subsequent ages have deemed not only false but absurd. As he points out, “there is the greatest difference between presuming an opinion to be true because, with a very little opportunity for contesting it, it has not been refuted, and assuming its truth for the purpose of not permitting its refutation.” And equally sensibly: “wrong opinions and practices gradually yield to fact and argument.” He then reminds us of the case of Socrates, who was put to death for voicing unacceptable opinions, and warns of blasphemy laws as an instrument of control.