27. The Modern Theory of Keynesian economists evolved bécause which original Keynesian assumption was no longer true in the post-wW economy? 28. Monetarist Theory evolved because Monetarists believed that the economic problem ofwas the only problem that should be focused on. The economic problem ofwould easily be resolved by letting the market take care of it without interference from any government agency. 29. Supply-side Theory has the(most/least/ most compelling) research behind it of all the macroeconomic theories Solution Post-Keynesian economics refers to a collection of emerging schools within macroeconomics that are attempting to \"go back to the basics\" of the work of John Maynard Keynes. In the post- World War II era, after Keynes died, his theories merged with more neoclassical-oriented thought and became the schools called New Keynesianism and neo-Keynesianism. These schools sought to root Keynes\' ideas in a microeconomic approach. Post-Keynesians, by focusing more on macro-effects, have in one way moved closer back to Keynes inflation and inflation least compelling research because they believe on micro economics variable.