In 1906, Alfred Henry Lewis stated, “There are only nine meals between mankind and anarchy.” Since then, his observation has been echoed by people as disparate as Robert Heinlein and Leon Trotsky.

The key here is that, unlike all other commodities, food is the one essential that cannot be postponed. If there were a shortage of, say, shoes, we could make do for months or even years. A shortage of gasoline would be worse, but we could survive it, through mass transport or even walking, if necessar...