  Why is relativity to a prior probability distribution (paradigm, inductive method) any more threatening to the idea of evidence as neutral arbiter than the previously mentioned relativity to background theory? The difference is this: when I fail to treat Koplik spots as evidence of measles, there is a clear and straightforward sense in which my background theory is inferior to yours. By contrast, proponents of the views presently under consideration typically insist that a relatively wide range of prior probability distributions (confirmation functions, inductive methods, paradigms) might be equally good. For this reason, such views are often criticized on the grounds that they turn the relationship between evidence and theory into an overly subjective affair.