The Widest Cleft in Statistics - How and Why Fisher opposed Neyman and Pearson

The paper investigates the “widest cleft”, as Savage put it, between frequencists in the foundation of modern statistics: that opposing R.A. Fisher to Jerzy Neyman and Egon Pearson. Apart from deep personal confrontation through their lives, these scientists could not agree on methodology, on definitions, on concepts and on tools. Their premises and their conclusions widely differed and the two groups they inspired ferociously opposed in all arenas of scientific debate. As the abyss widened, with rare exceptions economists remained innocent of this confrontation. The introduction of probability in economics occurred in fact after these ravaging battles began, even if they were not as public as they became in the 1950s. In any case, when Haavelmo, in the 1940s, suggested a reinterpretation of economics according to the probability concepts, he chose sides and inscribed his concepts in the Neyman-Pearson tradition. But the majority of the profession indifferently used tools developed by each of the opposed groups of statisticians, and many puzzled economists chose to ignore the debate. Economics became, as a consequence, one of the experimental fields for “hybridization”, a synthesis between Fisherian and Neyman-Pearsonian precepts, defined as a number of practical proceedings for statistical testing and inference that were developed notwithstanding the original authors, as an eventual convergence between what they considered to be radically irreconcilable.