 Mill’s entire philosophical outlook is informed by a spirit of naturalism (Skorupski 1989: 5ff.). It is not easy, however, to get a foothold on this naturalism. Mill’s general picture of mind and world is established by appealing to what we are warranted in believing about the nature of those objects—and hence relies on a substantive account of knowledge. His account of knowledge, however, draws upon his general picture of mind, world, and their relation—and therefore depends on a theory of what there is. This circularity will be discussed in  §3.7.  As an entry point into Mill’s overall system for the purposes of exposition, however, we might simply note Mill’s commitment to the claim that human beings are wholly part of nature, keeping in mind that Mill does not think of this as his unsupported starting point, but itself a substantive claim.