Are you, or is someone you know, a gadget freak? If so, you doubtless know that Wednesday was iPhone 5 day, the day Apple unveiled its latest way for people to avoid actually speaking to or even looking at whoever they’re with.

So is the new phone as insanely great as Apple says? Hey, I’ll leave stuff like that to David Pogue. 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.

Before I get there, let’s talk about where the buzz is coming from.

A recent research note from JPMorgan argued that the new iPhone might add between a quarter- and a half-percentage point to G.D.P. growth in the last quarter of 2012. How so? First, the report argued that Apple was likely to sell a lot of phones in a short period of time. Second, it noted that although iPhones are manufactured overseas, most of the price you pay when you buy one is domestic value-added — retailing and wholesaling, advertising and profits — all of which counts as part of G.D.P. Finally, it took some plausible guesses about the price of each phone and the number of phones sold, and used those guesses to make an estimate of the impact on G.D.P.