Having read Consciousness Explained by Daniel C. Dennett, I am very grateful to the author of this excellent book for setting out what amounts to a promising basis for furthering the understanding of consciousness, which has defied, and still defies, explanation. Professor Dennett gives a persuasive account of the computational nature of the neurological systems of the brain and nervous system that give rise to consciousness, and the pains he has taken to do so in this book are admirable. My only reservation is that he may have left out of the scope of his explanation something I have always thought to be essential to consciousness, namely life.
In Consciousness Explained and elsewhere Professor Dennett maintains the view that consciousness consists only in computational systems that can be copied in man-made machines. On what I must admit are purely intuitive grounds I find myself unable to accept this view. I have always experienced consciousness as an aspect of being alive; so, while I am happy to learn of the computational complexity that humans have evolved for rational consciousness, it seems that a similar computational complexity in a man-made machine might render it capable of much the same kind of reasoning activities as humans are capable of without any consciousness at all, simply because such a machine is still an inanimate object, immensely more complex than a laptop computer or an adding-machine or a doorbell but no more conscious.
Every form of living organism displays a sensitivity to its environs that distinguishes it from inanimate things and indicates its inherent ability to distinguish between itself and its surroundings in its self-motivated actions, and it is this basic characteristic of the living organism that seems to be at the base of consciousness. Various levels of consciousness are discernible in the array of lifeforms found on Earth and can be related to the varying degrees of neurological sophistication, culminating the rational consciousness made possible by the human brain. Whereas I would not want to take anything away from Professor Dennett’s ground-breaking work on the question of consciousness, I do think (again admittedly on purely intuitive grounds) that a complete explanation of consciousness will not be possible until experts in the life sciences can explain life itself.
It is when lifeforms have developed the computational neurological systems such as those of the human organism that rational consciousness emerges. When life itself has been explained fully and the relation between consciousness and life elucidated, the options open to humankind, it seems to me, will include not only making very clever robots but also making new living organisms. I will leave the speculation there, and ask others here what they think about this question of consciousness.