 A more pressing question still is whether Mill’s picture truly is coherent. As discussed above, Mill’s naturalistic approach drives him, via his inductivism and endorsement of the Relativity of Knowledge, towards idealism. Ultimately, he holds, the only things that we can be warranted in believing are permanent possibilities of sensation. But such objects are not—at least not obviously—natural entities. Mill is never entirely clear about the status of the permanent possibilities of sensation. To the extent that they are ideal objects, we might doubt their status as natural entities; the further reified such entities are in relation to actual sensations, the less plausible it is to characterise the inference from sensation to the possibility of sensation as an inductive one. Whether Mill’s naturalism is compatible with his idealism is very much an open question.