Must-Read: I think the very-sharp Ryan Cooper has gotten this mostly wrong. The two questions are (a) how much higher could expansionary fiscal and cooperative monetary policy permanently push annual GDP up above its current trend without triggering massive inflation, and (b) how large would the expansionary policies have to be to push the economy up that far? My guesses are 5% to (a)–that we could permanently raise annual GDP $800B relative to our current trajectory without triggering an upward spiral in inflation–and that we would need $300B more of annual government spending to get us there:

Ryan Cooper: Who’s Afraid of John Maynard Keynes?: “Does the economy have room to grow?…

…Could we create many more jobs and wealth if we really tried, or have we reached the limits of what we can produce? This… is at the heart of a recent dispute among academic economists… nominally centered on Bernie Sanders’ economic plan, but also illustrates a major fault line in the practice of theoretical economics today…. [Gerald] Friedman… assumed a model in which Sanders’ huge stimulus would push the economy up to full capacity (meaning full employment and maximum output), after which it would stay permanently at a higher level…. However, the key assumption behind the mainstream model is that an economy always tends towards full employment…. [But] even by conservative assumptions we are still something like $500 billion under total economic capacity, productivity has been consistently very weak, and there is absolutely nothing on the horizon that looks like it will return us to the level of employment we had in 2007, let alone 1999…. What’s more, a Friedman-style model in which a stimulus delivered to a depressed economy returns it to full capacity, after which it stays there, is not ridiculous…