Investors were spooked last week by suggestions that global growth may be slowing. Germany came in for particular attention as industrial production and exports both fell, warning that a recession may be on the way. World leaders, especially in Europe, are once again claiming that salvation can come only when Germany finally abandons its rigorous fiscal austerity and launches a Keynesian spending binge. This is preposterous.

To start, Germany’s current fiscal posture isn’t austere. “Austerity” suggests a pro-cyclical…