 In Kant (1781/7), the notion that consciousness is unified is central to his ‘transcendental deduction of the categories’ (see the entry on  Kant’s view of the mind and consciousness of self  for a fuller treatment of Kant). There Kant claims that in order to tie various objects of experience together into a single unified conscious experience of the world, we must be able to apply certain concepts to the items in question. In particular, we have to apply concepts from each of four fundamental categories of concept: quantitative, qualitative, relational, and what he called ‘modal’ concepts. Kant’s attempt to link the unity of consciousness to the structure of knowledge continues to capture the imaginations of philosophers: Arguments of this form can be found in P. F. Strawson (1966), Cassam (1996), Hurley (1994, 1998) and Revonsuo (2003), and are examined critically in  Section 7.3  and in Brook (2005). 