Gray's integration of the different levels of description and explanat
ion in his theory is problematic: (1) The introduction of consciousnes
s into his theorising consists of the mind-brain identity assumption,
which tells us nothing new. (2) There need not be correlations between
levels of description. (3) Gray's account does not extend beyond ''br
ute'' correlation. Integration must be achieved in a principled, mutua
lly constraining way.