Shortage of marshmallows I'm afraid



'... full employment depends on high investment rates that match high saving rates'



What makes you think there will ever be full employment, critically youth unemployment has done nothing but uptick longterm. As youth is the engine that in turn become tax revenues if employed it points to an underlying major problem



'...high private investments by business depend on high public investments in infrastructure and human capital'



Developed economies generally have the roughly the same direct and indirect tax regime and the tax take is dominated by welfare and healthcare demanded via the ballot box by a aging demographic. Significant investment in infrastructure cannot happen without raising tax levels or cutting expenditure. Raising tax levels in an aging demographic is problematic, cutting expenditure is problematic at the ballot box



The world is going to have to accept moderate growth and the aging demographic will have to accept reductions in support



It doesnt make any difference how cheap China makes stuff - if there is no disposable income there will not be consumption. Chinas success has been seizing manufacturing from the West, that was a transition and like all transitions has an end point which we are actually nearing. Seizing manufacturing is nothing clever, it is low cunning. China now has to do something more clever to grow. China will also quickly find out how rapidly cash in the bank can evaporate



'Shortsighted macroeconomists say the world is under-consuming; in fact, it is underinvesting'



Really, and who is supposed to make this investment. Let me guess China and the West. As pointed out above China is in a fix, its engine is due to misfire, and the West has its own problems



'Sustainable Development Goals adopted last September by all 193 members of the United Nations'



I'll wait to see with interest just how much of the load is shared between all 193 signatories, my guess is it will be skewed with the usual culprits



There has been significant progrees with raising many out of poverty worldwide. That has been done in a period when private and public debt in developed economies has soared. If there is any linkage in those two events you can expect progress to more difficult because very simply the capacity for debt has reached saturation point in the West



