For example: A braindead person is a body from which consciousness has fled, in which no human thought processes inhere. The body still maintains biostasis of a kind, and reacts in certain ways to its environment, but not in a fashion categorically different from that in which a slime colony or a pitcher plant does. You would say, then, that he does not have consciousness. Now imagine a normal person who has a degenerative disorder which causes him to progress inexorably from normalcy to braindeath. At some point, you'll have to say, he transits instantly from consciousness to the lack of it, since there is no smooth hierarchy of consciousness. People have it, but slime colonies and anything resembling them do not. Maybe 57, 436, 232 is the minimum number of connected dendrites required for consciousness (substitute whatever kind of threshold you find plausible). But then you have to say that there's something special about a brain with 57, 436, 232 connected dendrites, which permits it to be conscious, but which doesn't apply to a brain with 57, 436, 231 connected dendrites.