Bayesian methods are ubiquitous in contemporary observational cosmology. They enter into three main tasks: (I) cross-checking datasets for consistency; (II) fixing constraints on cosmological parameters; and (III) model selection. This article explores some epistemic limits of using Bayesian methods. The first limit concerns the degree of informativeness of the Bayesian priors and an ensuing methodological tension between task (I) and task (II). The second limit concerns the choice of wide flat priors and related tension between (II) parameter estimation and (III) model selection. The Dark Energy Survey (DES) and its recent Year 1 results illustrate both these limits concerning the use of Bayesianism.

贝叶斯方法在当代观测宇宙学中无处不在。它们承担了三个主要任务：（I）交叉检查数据集的一致性；（II）确定宇宙学参数的约束；（三）选型。本文探讨了使用贝叶斯方法的认识论限制。第一个限制涉及贝叶斯先验的信息量以及任务（I）和任务（II）之间随之产生的方法上的张力。第二个限制涉及宽平板先验的选择以及（II）参数估计和（III）模型选择之间的相关张力。暗能量调查（DES）及其最近的1年级结果说明了有关使用贝叶斯主义的这两个限制。