Why I am not a Bayesian

9 Sep, 2013 at 19:52 | Posted in Theory of Science & Methodology | 3 Comments

What I do not believe is that the relation that matters is simply the entailment relation between the theory, on the one hand, and the evidence on the other. The reasons that the relation cannot be simply that of entailment are exactly the reasons why the hypothetico-deductive account … is inaccurate; but the suggestion is at least correct in sensing that our judgment of the relevance of evidence to theory depends on the perception of a structural connection between the two, and that degree of belief is, at best, epiphenomenal. In the determination of the bearing of evidence on theory there seem to be mechanisms and strategems that have no apparent connection with degrees of belief, which are shared alike by people advocating different theories. Save for the most radical innovations, scientists seem to be in close agreement regarding what would or would not be evidence relevant to a novel theory; claims as to the relevance to some hypothesis of some observation or experiment are frequently buttressed by detailed calculations and arguments.All of these features of the determination of evidential relevance suggest that that relation depends somehow on structural, objective features connecting statements of evidence and statements of theory. But if that is correct, what is really important and really interesting is what these structural features may be. The condition of positive relevance, even if it were correct, would simply be the least interesting part of what makes evidence relevant to theory.

None of these arguments is decisive against the Bayesian scheme of things … But taken together, I think they do at least strongly suggest that there must be relations between evidence and hypotheses that are important to scientific argument and to confirmation but to which the Bayesian scheme has not yet penetrated.

Clark Glymour