  The extent to which observation is theory-laden remains a contested  matter.[34]  To the extent that evidence which bears on a theory does not admit of a neutral characterization among those with sufficiently different theoretical commitments, this threatens to limit the ability of such evidence to successfully discharge the role of neutral arbiter in such cases. Still, whatever concessions to the proponents of theory-ladenness might be in order, the significance of the doctrine that they defend should not be overstated. For in any case, it seems undeniable that theories sometimes are discredited by the emergence of evidence which is taken to undermine them—even in the eyes of their former  proponents.[35]  Let's assume then that evidence sometimes does successfully discharge the function of neutral arbiter among theories and is that which secures intersubjective agreement among inquirers. What must evidence be like, in order for it to play this role? That is, given that evidence sometimes underwrites intersubjective agreement, what constraints does this place on answers to the question: what sorts of things are eligible to count as evidence?