The most important recent development in macroeconomic theory seems to me describable as the reincorporation of aggregative problems such as inflation and the business cycle within the general framework of microeconomic theory. The concept of rational expectations was first developed by John Muth and later applied to macroeconomics by Robert Lucas. Macroeconomic models building on rational expectations microfoundations impute beliefs to the agents that are not based on any real informational considerations, but simply stipulated to make the models mathematically-statistically tractable. The analogy between microeconomic behaviour and macroeconomic behaviour is misplaced. Empirically, science-theoretically and methodologically, neoclassical microfoundations for macroeconomics are defective. Its ultimate building-block is the perception of genuine uncertainty and that people often simply do not know. Economists defending the microfoundationalist programme often also maintain that there are no methodologically coherent alternatives to microfoundations modelling economic models based on the choices and acts of individuals is the only scientific game in town.