The purpose of this dissertation is to investigate the connections between metaphysical naturalism and the categorical ignorance thesis – offered by Rae Langton (1998), David Lewis (2009), Frank Jackson (1998), and Simon Blackburn (1990) – and determine whether the latter will challenge the former. According to metaphysical naturalism, the actual world contains only metaphysically natural things. According to the categorical ignorance thesis, all we can know about things are their dispositional properties, but the categorical properties that bear these properties remain in principle unknowable. In this dissertation, I will determine whether the ignorance of categorical properties – as Rae Langton (1998), David Braddon-Mitchell and Frank Jac...