Fish stock assessment as a non-falsifiable science: replacing an inductive and instrumental view with a critical rational one

Abstract A logical analysis of the common fisheries models used in stock assessment has shown that they produce specific predictions with the logical form of existential statements and cannot be falsified or tested by the empirical evidence. By contrast, the Gordon–Schaefer model of fisheries economics makes predictions, not in the form of existential statements, but in the form of universal patterns that exclude possibilities. This economic version of the Schaefer model is falsifiable, since from the logical point of view, the excluded possibilities represent potential falsifications or tests of the model. Management choices are presently guided by quantified predictions produced by those fisheries models best supported by the facts or data—a pragmatic approach to prediction that involves an inference from past experience and makes the implicit assumption that the future will be largely like the past. If management decisions are to be based on valid arguments then this inductive approach has to be replaced by a critical rational approach in which management choices are based, not on those non-falsifiable models best supported by the facts, but on those falsifiable models that have been the best tested by the facts—a critical rational thesis illustrated by the Gordon–Schaefer model of fisheries economics.