 The fact that firms appear to be consistently heterogeneous (S.F.3) has brought Dosi to criticize the Neoclassical prediction that firms in an industry converge toward some kind of "optimal" or "representative" characteristic.For such argument to be valid, the characteristics of firms would need to evolve in time toward a normal distribution, possibly showing some shrinking of the support.Notably, this theoretical implication poses an unresolved challenge to the arguments put forward by Milton Friedman in his essay "The Methodology of Positive Economics".