“THE little screaming fact that sounds through all history”, John Steinbeck wrote, is that “repression works only to strengthen and knit the repressed.” The standard Western critique of skull-crackers on the streets of Cairo, Moscow or Tehran is “You will regret it.” But will they? History’s lessons regarding protests and violence are more complex. Bloodshed sometimes works for autocrats, at least temporarily. But for protesters themselves, taking up arms is usually a mistake.

Massacres do indeed leave the culprits isolated on the international stage and reviled at home, as citizens lose any illusions they might have harboured about their rulers. But, at least in the short term, they often keep regimes in power. China’s Communist rulers see the deaths on Tiananmen Square in 1989 as blood well spilled. Doubtless Iran’s have few regrets about the people they killed in 2009. Bashar Assad may feel that his atrocities in Syria have been vindicated. In this narrow sense—even if observers might wish otherwise—violence often succeeds.

History’s consolation is that, in the end, such brutality can backfire. Research by Christian Davenport of the University of Michigan and Benjamin Appel of Michigan State University suggests that, on average, harsh repression shortens leaders’ tenure. In Mr Davenport’s formulation, violence “sets in motion a process that can result in their removal.”

The first risk for despots is that a crackdown may flop: troops and goons cannot or will not always enact emergency laws or obey orders to shoot. In such cases, they are often done for. The Soviet Union survived on coercion and collapsed when that failed. Disobedient security services helped finish Ferdinand Marcos in the Philippines and Slobodan Milosevic in Serbia.

Even when orders are obeyed, as Steinbeck noted, repression can ultimately strengthen the opposition. Barbara Walter of the University of California, San Diego points to Suharto’s abuses, as president of Indonesia, against separatists in Aceh. An onslaught in 1989 suppressed the rebellion—only for it to flare up, with broader support, a decade later. Britain’s General Reginald Dyer, responsible for killing hundreds of Indians at Amritsar in 1919, said: “I thought I should shoot well and shoot strong, so that I or anybody else should not have to shoot again.” He was wrong.

Egypt’s generals, like other trigger-happy leaders, should note that blood tends to complicate the personal retirement plans of the bloodied—as the Shah of Iran (exiled), Saddam Hussein (executed) and Muammar Qaddafi (died in a ditch) might have attested. Resentment over the Russian demonstrators killed in 1905 helped to doom Tsar Nicholas II 13 years later.

It is not only the autocrats who are tempted by violence, of course. For gassed, battered and bullet-ridden protesters, the urge to meet force in kind is strong. And, in a few cases, such as Northern Irish republicanism, cultivating a deadly wing has helped dissidents, partly by increasing the appeal of the moderates. The IRA’s bombs eventually helped to push British governments into talks on political compromise.

But history suggests that, for most protest movements, violence is counterproductive: those that turn the other cheek, opting for civil disobedience, sit-ins and strikes rather than armed retaliation, tend to do best. Erica Chenoweth of the University of Denver and Maria Stephan of America’s State Department analysed protests designed to remove governments, expel occupiers or win secession between 1900 and 2006. From 1960 onwards, they found, “non-violent resistance has become more frequent and more successful, whereas violent campaigns are becoming less frequent and increasingly less successful.” Overall, they conclude, peaceful uprisings are twice as likely to succeed as violent ones (even if the current protests in Bulgaria have yet to achieve much).

That rule has an important condition: unity. A split protest movement, divided between pacifists and petrol-bombers, is ideal for tyrants. Keeping every cheek turned takes discipline and firm leadership, exemplified by Mahatma Gandhi and Martin Luther King. But when demonstrators manage that, they can ensure that all the opprobrium is focused on the state and, despite the risks to life and limb, recruit more supporters.

This objective—winning the moral battle, rather than the street fight—has become more crucial in the internet and satellite-TV age. Even in places such as Egypt, where much of the domestic media is state-friendly, images of corpses seep out. Even without direct foreign intervention, officials begin to worry about the security of their assets and ability to travel abroad. Defections become more likely.

Luckily for today’s protesters, there are precedents to emulate. From the uprisings at the end of the cold war, to Serbia in 2000, to the “colour revolutions” in Georgia and Ukraine, techniques have evolved that increase the cost of state abuses and make the opposition’s innocence plain. In Kiev during the orange revolution of 2004, for instance, cordons around marches made it hard for provocateurs to incite skirmishes that would tarnish the orange side as hooligans. Twitchy riot police were met by pretty young women carrying roses.

There is a paradox at the heart of state violence. For bogus regimes, the threat of force is not an aberration but the mainstay of their control. Yet, by demonstrating their illegitimacy, it is also proof of their fragility. As Ms Chenoweth puts it, “the more violence a regime uses to survive, the less power it actually has.” That can be a source of strength for protesters—if they use it wisely, and even if it hurts.