  According to this picture, a central function of evidence is to serve as a neutral arbiter among rival theories and their adherents. Whatever disagreements might exist at the level of theory, if those who disagree are objective, then the persistence of their disagreement is an inherently fragile matter, for it is always hostage to the emergence of evidence which decisively resolves the dispute in one direction or the other. Our ability to arrive at consensus in such circumstances is thus constrained only by our resourcefulness and ingenuity in generating such evidence (e.g., by designing and executing crucial experiments) and by the generosity of the world in offering it up.