  In order to abstract from the contingencies of our epistemic situation, arguments about tractability usually proceed by considering highly idealised subjects, in particular subjects whose factual, logical, etc. knowledge far exceeds ours. But the problem with such idealisations is that they seem question-begging. For example, a theological anti-naturalist would maintain that factually highly-informed subjects will be apprised of facts about supernatural reality. Our grip on idealised subjects and how disagreement between them is likely to resolve itself may therefore be too loose to draw any substantive morals from such thought experiments. Either that or such arguments are likely to be question-begging. 