Is the study of macroeconomic fluctuations "scientific"?

Summary The study of macroeconomic fluctuations is based on the principle that the behavior of the whole (the aggregates) cannot be reduced to the sum of the parts (the agents, the markets). This is so because interdependencies between markets can substantially amplify, or on the contrary dampen, the shocks that at any moment disturb the equilibrium. Understanding these general equilibrium effects, for which direct evidence is limited, confounding factors are numerous, and controlled experiments are impossible, is necessarily more conjectural - but no less "scientific" - than the study of individual behaviour or of an isolated market. Ignoring these effects on the grounds that they do not have the same degree of empirical certainty as a directly observed microeconomic effect can lead to serious policy errors.