"So many challenges could be overcome if we just get this economy growing at full strength. There is not a reason in the world why we cannot grow at a rate of four percent a year. And that will be my goal as president -- four percent growth, and the 19 million new jobs that come with it."
[S]imple math suggests the next president is unlikely to see sustained 4 percent G.D.P. growth absent a remarkable, rapid upward shift in the nation's productive capacity. [...] [F]or 4 percent growth to be realistic in the next presidential term -- not just for a one-quarter spurt but on a sustained basis -- one of two things must apply. Either the technocrats at places like the C.B.O. and the Fed must be wildly underestimating the nation's growth potential today. Or a revolution in American productivity must be on the way. Neither of those are things that a president has much control over.