What I’m interested in, instead, are suggestions that the unveiling of the iPhone 5 might provide a significant boost to the U.S. economy, adding measurably to economic growth over the next quarter or two.

Do you find this plausible? If so, I have news for you: you are, whether you know it or not, a Keynesian — and you have implicitly accepted the case that the government should spend more, not less, in a depressed economy.

A strong argument for Keynesian stimulus. More spending is healthy.