Descriptive, Predictive And Normative Theory

The higher degree of description is reached when a field becomes amenable to the use of the axiomatic method. In economics this state has been reached only recently in the establishment of a numerical utility. In general, it is difficult to know what to describe and how to measure; both require precise concepts. Current economic descriptions lack both very often, in particular the whole area of psychological factors, decisions, etc., escape the essentially physical descriptions of economic phenomena. Good predictions are the ultimate test of theory but also false theories often have a surprising power to predict. Thus, this matter is much more complicated than normally assumed. Even descriptive theories can be interpreted as ‘normative’ provided they are convincing to the user. The implied norm is often a prohibition, as for example, in the statement that one should not try to build a perpetuum mobile. If a state of society is commonly accepted which sanctions private property, then the norm follows that one ought not to steal. This is different from normative value statements that derive solely from other norms.