run on a while longer. you also talk about peak growth. what do you mean by that? there s a sense in which we have reached the maximum growth potential of particularly the developed world. your unemployment rates are at a 40-year low. that just tells us the number of new people we can find to get to work is a lot lower than we imagined. this is counter to the conventional wisdom about robots coming to steal your job and auto making and stuff like that. but the importance of demographics has still not been realized by people. the global economy grew by 4% between 1950 and 2008. that s kind of the anchoring biassed. that s what the economy should be growing at. the u.s. economy should be growing at 3% to 4%. what we re forgetting is that that was the only time in history that the economy grew at such a robust pace, and the reason for that is that we had a