One of my favourite cartoons shows an elderly, professorial-looking man talking to a much younger fellow, possibly a student. “Those who don’t study history,” says the old guy, “are doomed to repeat it.” He then adds, “Yet those who do study history are doomed to stand by helplessly while everyone else repeats it.”

Like many jokes, this one works because it contains a kernel of truth. But I still believe that it is better to try to find out what really happened in the past, even when doing so is uncomfortable. A decent, open society should never flinch from attempting to discover how yesterday helped to make today, and how we could use the experience to create a better tomorrow.

This can, of course, make history a cleansing, if sometimes insurrectionary, subject. That is one reason why authoritarian states want to impose their own fictive but politically expedient narratives. But open, democratic societies that value freedom need to be brave and honest about their own histories as well.

For example, the history of Britain’s involvement in Ireland contains more than its ration of shameful episodes. I come from a family, on my father’s side, of potato-famine emigrants from 19th-century, British-run Ireland. At least 1 million people died in the famine, and perhaps as many as 2 million left Ireland to save their lives and those of their families.

The creation in 1921 of Northern Ireland—a gerrymandered structure designed to buy off hardline Protestant militants—established a statelet that for more than 50 years trampled the civil rights of its Catholic minority. Members of Parliament at Westminster, principally Conservatives, often denounced rights abuses and oppression in other countries, including the racial segregation and disenfranchisement in the American South. But they turned a blind eye to what was happening in Northern Ireland, which the Sunday Times once famously called “John Bull’s political slum.”

All this explains why the 1998 Good Friday Agreement, which brought peace at last to the province, was such a historically important breakthrough in Britain and Ireland’s political life. It also underscores the importance of protecting the accord against the threats posed to it, almost casually, by Prime Minister Boris Johnson and right-wing Conservatives. They are trying to pressure the European Union by saying that they will walk away from what they promised the Republic of Ireland and Northern Ireland regarding trade and border arrangements in the United Kingdom’s negotiated Brexit agreement.

We also have to look honestly at other aspects of our history. I am not seeking to encourage an anarchic cultural revolution in Britain that tears down every sign of anything conceivably associated with the least defensible parts of the country’s history. But I believe that we should welcome attempts to deepen the public’s understanding of the relationship between the slave trade and the sugar and cotton industries, and of the development of the Atlantic economy and political culture.

After all, as the former New York Times correspondent Howard W. French argues convincingly and with considerable intellectual force in his recent book Born in Blackness, Britain was one of the most significant players in the scramble for Africans, and not just for Africa. French’s book presents arguments that have been too seldom heard in Britain.

On this and other issues, we need serious, mature, and informed debate, not the shouting of slogans. There is no country in the world whose history is simply a parade of virtuous heroes and moral triumphs.

That said, there is a strong relationship between freedom of speech and propaganda-free education on one hand, and honesty about history on the other. When Russian President Vladimir Putin’s government recently closed down the human-rights group Memorial International, which since 1989 had uncovered the stories of many Stalin-era deaths and disappearances, it was trying to reduce further the possibility of criticism and dissent today. And an online video allegedly showing Putin’s lavish personal palace by the Black Sea has to be wiped from the internet in case too many Russians compare his standard of living with their own.

Likewise, when Chinese President Xi Jinping’s regime targets so-called historical nihilism, it is attacking anything that contradicts the Communist Party of China’s official version of history. The aim is to bury any debate about the CPC’s past cruelties.

How many people died in the famine triggered by Mao Zedong’s lunatic Great Leap Forward? How many were killed in and around Tiananmen Square in 1989? How many have been locked up in Xinjiang? How many Muslim women have been raped and subjected to forced abortions and sterilisations? According to the CPC leadership, asking these questions demonstrates insufficient love of China. But why must one love Xi’s dictatorship in order to show love for a country with such a long and rich history of spectacular achievements?

That is why the majority of those who live in Hong Kong, who come from families that fled communist brutality, cannot accept that, to demonstrate their patriotism, they must love the CPC. They can remember all too clearly what happened in Tiananmen Square. The CPC cannot erase that event from history by tearing down the memorials for its victims in Hong Kong, like the “Pillar of Shame” sculpture, nor by prosecuting people for participating in a candlelight vigil for the dead on June 4 every year.

China’s communist leaders cannot hold onto the present and the future by writing a fabricated version of the past. Hong Kong residents’ memories and fundamental commitment to decency and freedom will at some point ensure them a better future. They will then be able to do all Chinese the great cultural and political service of reminding them what really happened under communism.

That prospect should encourage supporters of liberal democracy and open societies everywhere. When it comes to examining the past, the truth can sometimes be painful, but honesty is the best policy.

—Project Syndicate