By moving towards sharply higher minimum wages, policymakers are accelerating into a fog. Little is known about the long-run effects of modest minimum wages. And nobody knows what big rises will do, at any time horizon. It is reckless to assume that because low minimum wages have seemed harmless, much larger ones must be, too.
One danger is that a high minimum wage will push some workers out of the labour force for good. A building worker who loses his job in a recession can expect to find a new one when the economy picks up. A cashier with few skills who, following the introduction of a high minimum wage, becomes permanently more expensive than a self-service checkout machine will have no such luck.