Mr. Obama’s analogies to the Great Depression are not only historically inaccurate, they’re also dangerous. Repeated warnings from the White House about a coming economic apocalypse aren’t likely to raise consumer and investor expectations for the future. In fact, they have contributed to the continuing decline in consumer confidence that is restraining a spending pickup. Beyond that, fearmongering can trigger a political stampede to embrace a “recovery” package that delivers a lot less than it promises. A more cool-headed assessment of the economy’s woes might produce better policies.