‘Nothing is more difficult,’ wrote the German political essayist Kurt Tucholsky in 1921, ‘and nothing requires more character, than to find yourself in open contradiction to your time and loudly to say: No.’ First of all, it is intellectually and psychologically difficult to step outside the received wisdom of your time and place. What has been called ‘the normative power of the given’ persuades us that what we see all around us, what everyone else seems to regard as normal, is in some sense also an ethical norm.

Numerous studies in behavioural psychology show how our individual conviction of what is true or right quails before the massed pressure of our peers. We are, as Mark Twain observed, ‘discreet sheep’. This is what John Stuart Mill picked up when he wrote in On Liberty (1859); that the same causes that make someone a churchman in London would have made him a Buddhist or a Confucian in Beijing. The same truth is gloriously captured in the humorous song ‘The Reluctant Cannibal’ (1960) by Michael Flanders and Donald Swann, in which a young cannibal revolts against the settled wisdom of his elders and declares that ‘eating people is wrong’. At the end of the song, one of the elders exclaims, to huge belly laughs all round: ‘Why, you might just as well go around saying: “Don’t fight people!”’ Then he and his colleagues cry in unison: ‘Ridiculous!’

Yet norms change even within a single lifetime, especially as we live longer. So as elderly disc jockeys are arrested for sexual harassment or abuse back in the 1960s, we should be uncomfortably aware that some other activity that people regard as fairly normal now might be viewed as aberrant and abhorrent 50 years hence.

To step outside the established wisdom of your time and place is difficult enough; openly to stand against it is more demanding still. In Freedom for the Thought that We Hate (2007), his fine book on the First Amendment tradition in the United States, Anthony Lewis quotes a 1927 opinion by the Supreme Court Justice Louis Brandeis, which Lewis says ‘many regard as the greatest judicial statement of the case for freedom of speech’.

The passage Lewis quotes begins: ‘Those who won our independence… believed liberty to be the secret of happiness and courage to be the secret of liberty.’ This is magnificent, although it also illustrates the somewhat self-referential, even self-reverential, character of the modern First Amendment tradition.

Lewis cites Brandeis, who credits this thought to the 18th-century founders of the US. But those founders would have been well aware that they got it straight from Pericles’ funeral oration during the Peloponnesian War of the fifth century BCE, as reported – if not invented, or at least much improved upon – by Thucydides. ‘For you now,’ Thucydides’ Pericles admonishes his ancient Athenian audience, after praising the heroic dead, ‘it remains to rival what they have done and, knowing the secret of happiness to be freedom and the secret of freedom a brave heart, not idly to stand aside from the enemy’s onset.’

More directly, the US tradition of courage in the defence of free speech draws on the heritage of the 17th-century English. People such as John Lilburne, for example. In 1638, while still in his early 20s, Lilburne was found guilty by the Star Chamber court of helping to smuggle into England a tract against bishops that had been printed in the Low Countries. He was tied to the back of a cart on a hot summer’s day and unremittingly whipped as he walked with a bare back all the way from the eastern end of Fleet Street to Westminster Palace Yard. One bystander reckoned that he received some 500 blows that, since the executioner wielded a three-thronged whip, made 1,500 stripes.

Lilburne’s untreated shoulders ‘swelled almost as big as a penny loafe with the bruses of the knotted Cords’, and he was then made to stand for two hours in the pillory in Palace Yard. Here, in spite of his wounds and the burning sunshine, he began loudly to tell his story and to rail against bishops. The crowd was reportedly delighted. After half an hour, there came ‘a fat lawyer’ – ah, plus ça change – who bid him stop. The man whom the people of London had already dubbed ‘Free-Born John’ refused to shut up. He was then gagged so roughly that blood spurted from his mouth. Undeterred, he thrust his hands into his pockets and scattered dissident pamphlets to the crowd. No other means of expression being left to him, Free-Born John then stamped his feet until the two hours were up.

As an Englishman, I find particular inspiration in the example of Free-Born John, and those of all our other free-born Johns: John Milton, John Wilkes, John Stuart Mill (and George Orwell, a free-born John in all but name). More broadly, there is no reason to understate, let alone to deny, a specifically Western tradition of courage in the advancement of free speech, one that can be traced from ancient Athens, through England, France and a host of other European countries, to the US, Canada and all the liberal democracies of today’s wider West. But it would be quite wrong to suggest that this habit of the heart is confined to the West. In fact, there have been rather few examples of such sturdy defiance in England in recent times, while we find them in other countries and cultures.

Consider, for instance, the Chinese dissident Liu Xiaobo. Liu was sentenced to 11 years’ imprisonment in 2009 for ‘subverting state power’. Both his written response to the charges against him and his final speech in court are, like many of his earlier writings, lucid and courageous affirmations of the central importance of free speech. He definitely does not draw only on Western traditions. For example, in his book No Enemies, No Hatred (2012), he quotes a traditional Chinese 24-character injunction: ‘Say all you know, in every detail; a speaker is blameless, because listeners can think; if the words are true, make your corrections; if they are not, just take note.’

After paying a moving tribute to his wife (‘Armed with your love, dear one, I can face the sentence that I’m about to receive with peace in my heart’), Liu looks forward to the day ‘when our country will be a land of free expression: a country where the words of each citizen will get equal respect, a country where different values, ideas, beliefs and political views can compete with one another even as they peacefully coexist’. The judge cut him short in court before he had finished speaking, but free-born Xiaobo, like free-born John, still got his message out. In his planned peroration, Liu wrote: ‘I hope that I will be the last victim in China’s long record of treating words as crimes. Free expression is the base of human rights, the root of human nature and the mother of truth. To kill free speech is to insult human rights, to stifle human nature and to suppress truth.’

‘They will send me to prison,’ al-Johani says, ‘and I will be happy’

Liu was by this time famous, and that great speech made him more so. He was awarded the Nobel Peace Prize in 2010. But perhaps the most inspiring examples of all come from people who are not famous at all: so-called ordinary people doing extraordinary things. People such as the Hamburg shipyard worker who, at the launch of a naval training vessel in 1936, refused to join all those around him in making the Hitler salute. The photograph only achieved wide circulation on the internet more than 60 years later. There he stands amid a forest of outstretched arms, with both his own firmly folded across his chest, a portrait of stubborn worker’s pride. His name was August Landmesser. He had been a Nazi party member but was later expelled from the party for marrying a Jewish woman, and then imprisoned for ‘dishonouring the race’. After his release, he was drafted to fight in the Second World War and never returned.

Again, such moments are emphatically not confined to the West. During the Arab Spring of 2011, a ‘day of rage’ was proclaimed by dissidents in Saudi Arabia. Faced with a massive police presence at the appointed location in the country’s capital Riyadh, almost nobody showed up. But one man, a strongly built, black-haired teacher called Khaled al-Johani, suddenly approached a group of foreign reporters. ‘We need to speak freely,’ he cried, with an explosion of pent-up passion. ‘No one must curb our freedom of expression.’ A BBC Arabic service film clip, which you can watch on YouTube, shows a tall secret policeman, in white robes, headdress and dark glasses, looming in the background as he snoops on al-Johani’s speech. A little further away, armed police mutter into their walkie-talkies. ‘What will happen to you now?’ asks one of the reporters, as they escort the teacher back to his car. ‘They will send me to prison,’ al-Johani says, adding ironically: ‘and I will be happy.’ He was subsequently condemned to 18 months’ imprisonment.

In many places, we can find monuments to the Unknown Soldier, but we should also erect them to the Unknown Speaker.

This is an edited extract from ‘Free Speech: Ten Principles for a Connected World’ by Timothy Garton Ash © 2016, published by permission of Atlantic Books.