Confirmation: What's in the evidence?

Abstract

The difference between accommodated evidence (i.e. when evidence is known first and a hypothesis is proposed to explain and fit the observations) and predicted evidence (i.e., when evidence verifies the prediction of a hypothesis formulated before observing the evidence) is investigated. According to Bayesian confirmation theory, accommodated and predicted evidence constitute equally strong confirmation. Using a survey experiment on a sample of students, however, it is shown that predicted evidence is perceived to constitute stronger confirmation than accommodated evidence and in line with the decision analytical framework that is presented we show that predictions work as a signal about the scientists’ knowledge which in turn provides stronger confirmation. The existence of such an indirect relationship between hypothesis and evidence can be considered to impose undesirable subjectivity and arbitrariness on questions of evidential support. Evidential support is ideally a direct and impersonal relationship between hypothesis and evidence and not an indirect and personal relationship as it has shown to be in this paper.