Time-slice epistemology for Bayesians

Recently, some have challenged the idea that there are genuine norms of diachronic rationality. Part this challenge has involved offering replacements for principles. Skeptics about rationality believe we can provide an error theory it by appealing to synchronic updating rules that, over time, mimic behavior norms. In paper, I argue most promising attempts develop position within Bayesian framework unsuccessful. sketch a new surrogate draws upon features each these earlier attempts. At heart discussion is question what exactly means say one norm another. surrogacy, in given context, be taken as proxy degree which formal and traditional epistemology made compatible.