Scientific Disagreements and the Diagnosticity of Evidence: How Too Much Data May Lead to Polarization

: Scienti fi c disagreements sometimes persist even if scientists fully share results of their research. In this paper we develop an agent-based model to study the impact of diverging diagnostic values scientists may assign to the evidence, given their di ff erent background assumptions, on the emergence of polarization in the scienti fi c community. Scientists are represented as Bayesian updaters for whom the diagnosticity of evidence is given by the Bayes factor. Our results suggest that an initial disagreement on the diagnostic value of evidence can, but does not necessarily, lead to polarization, depending on the sample size of the performed studies and thecon fi denceintervalwithinwhichscientistssharetheiropinions. Inparticular,themoredatascientistsshare, the more likely it is that the community will end up polarized.