The monetary policy decision, as any other decision, is the product of a procedure assembling a lot of primary information, but also what type of other ingredients contribute finally to a certain monetary policy decision.

The paper analyses the presuppositions (often implicit) the actual quantitative and logical modelling is based on. In the context, some points of view are proposed, aimed at to eliminate or reduce the incertitude and vagueness generated by the actual way of understanding the macroeconomic modelling.