THE PRICE OF OIL has jumped about 7 percent in the past two weeks. Under ordinary circumstances, and for most commodities, volatility comes as no surprise and is of little consequence. But oil is different. For one thing, its price is affected by a powerful cartel, OPEC, that tries to lock in price increases. For another, it is so crucial to the functioning of industrial economies that past price jumps have thrown America and, in some cases, the world, into protracted periods of sub-par growth.

The major consuming countries long ago decided to acquiesce in the producing nations’ cartel behavior. In return, OPEC informally agreed to cap oil prices at around $28 per barrel. Never mind that over $20 of that price constitutes profits to the Saudi royal family and the typically unsavory rulers of other countries that sit atop the world’s oil reserves. Industrial countries figured that so long as prices stayed below the cartel cap, their economies would be able to grow at reasonable rates.