The Seven Year Itch fashioned a classic American romantic comedy around the notion that after seven years of marriage, a spouse’s interest in a monogamous relationship starts to wane. The premise of the Marilyn Monroe film made for some great laughs and iconic images, but it was not pure fancy. A lot of studies over time have shown that the average length of a first marriage is about seven or eight years.

There is an interesting parallel in politics; specifically, the life span of one-party regimes, though in this case we might call it the “70-year itch.” The U.S.S.R. is a prime example. By the time Mikhail Gorbachev took command of the Soviet Union in 1985, the rot in the Soviet system, and the corresponding decline of its legitimacy, were well advanced. “Interest in the marriage” had long since begun to wane.  Gorbachev’s efforts to revive it with political opening and economic reform (glasnost and perestroika) only enabled the marriage to break up peacefully. When the Soviet Union collapsed in 1991, the Communist Party had been in power for a little more than 70 years. Similarly, the Institutional Revolutionary Party (PRI) ruled in Mexico from its founding in 1929 until its defeat in the 2000 elections—71 years. 

Several of today’s remaining one-party authoritarian regimes have been in power 50 to 65 years, and there is good reason to think that they, too, are now facing the “70 year itch.” Part of the problem is that revolutionary one-party regimes like those in China, Vietnam, and Cuba cannot survive forever on the personal charisma of their founding leaders. Mao and Ho Chi Minh are long since gone, along with all the other leaders of the revolutionary founding generation, and in Cuba the Castro brothers are in their final years....