A favourite line of defence of embattled dictatorships is that, if their rule is relaxed, their country will be torn apart by ethnic, religious, or social strife.
Opponents of autocracy commonly respond that these fears are exaggerated and self-serving and it is dictators themselves who foment such divisions.
Both these arguments contain elements of truth and self-deception. In Iraq, under Saddam Hussein, many of his opponents genuinely believed that the divisions between Sunni, Shia and Kurd were primarily the result of his machinations.
Likewise, in Syria today, Bashar al-Assad has sought with some success to persuade the Alawites, Christians and other minorities, that they face oppression, if not slaughter, at the hands of Sunni insurgents.
A degree of self-deception about the extent of their own divisions is common to most cities and countries where different communities live side-by-side.
So how far do this apply to Syria after a year-and-a-half of escalating conflict?
Politicians, diplomats and journalists are aware of the dangers of communal strife in Syria.
There is also the knowledge that it is much in the interests of the Syrian insurgents to play up the example of Libya, where Nato intervention appeared to succeed, and downplay Iraq when looking for foreign support.
At this stage, most people who see news of fresh fighting and atrocities in Syria pay less and less attention to what is happening there. Syria comes across as one more murderous imbroglio, like Iraq, Somalia, eastern Congo or Lebanon used to be or remain today.
Television pictures of extreme violence in such places no longer shock because they are part of the expected landscape.
These expectations have numbed the outside world and most Syrians into paying too little attention to a crucial recent development in the Syrian crisis. It is an event likely to have immense impact not just on Syria, but on several of its neighbours. This is the withdrawal of almost all of the Syrian army in the north of the country along the Syrian border.
The Syrian Kurds (whose total numbers are about 2.5 million, or 10% of the Syrian population) have achieved de facto autonomy.
Both Bashar al-Assad and the Syrian rebels are vying for Kurdish support and have to accept, at least for now, the establishment of a Kurdish enclave.
The significance of what has happened is not immediately obvious until it is recalled that Kurdish nationalism is one of the great forces in Middle East politics.
The position of the Kurdish minorities in Iraq and Turkey is crucially important for their stability.
In Iraq, the Kurdistan Regional Government (KRG) enjoys autonomy from Baghdad. If the Syrian Kurds achieve the same status of autonomy, close to independence, as in Iraq, how will Turkey be able to deny similar status to its own Kurdish minority in the south-east of the country?
In the years since the PKK (Kurdistan Workers Party) started guerrilla war against the Turkish state in 1984, Ankara has failed to crush the insurgents politically or militarily.
In the past couple of years, the Turkish Prime Minister, Recep Tayyip Erdogan, has short-sightedly opted for repression rather than concessions.
Turkey may come to regret its intervention in Syria. Turkey threatens to invade northern Syria if the PKK gains control there, but since it has failed to eliminate the movement at home, it is unlikely to do so abroad.
In Washington, Ankara, Baghdad and elsewhere, there is alarm that the political chessboard of the Middle East has suddenly changed in an unexpected way.
"The real fear isn't that Syria will be divided," says Aliza Marcus, an expert on the Turkish Kurds. "It's that the Kurds are uniting."