  The move that Kant makes next is interesting. He argues that the mind could not use concepts so as to have unified objects of representation if its consciousness were not itself unified (A107–108). Why does consciousness and its unity appear here? We have been exploring what is necessary to have experience. Why would it matter if, in addition, unified consciousness were necessary? As Walker (1978, p. 77) and Guyer (1987, pp. 94–5) have shown, Kant did not need to start from anything about the mind to deduce the Categories. (A famous footnote in The Metaphysical Foundations of Natural Science [Ak. IV:474fn.] is Kant’s best-known comment on this issue.) So why does he suddenly introduce unified consciousness?