Blackmore asks each subject the same questions (mostly), and I thought it would be a handy guide to summarise their answers in individual posts, starting with a question which attempts to frame the whole subject: what is the problem of consciousness?
I will only offer outlines of and quotes from their answers; buy the book for the Full Monty. Be aware that quote context is important, and I'm focussing on those comments that seem particularly relevant to me.
Bernard Baars: slightly avoided the question, but I could summarise as: what is the difference between knowledge which is conscious and knowledge which is unconscious?
Ned Block: "The problem is, what is consciousness? More specifically, I'm interested in what consciousness is in the brain." Consciousness is the "technicolour phenomenology; the 'what it's like'."
David Chalmers: "We can be terribly objective, but something very important about being a human being is left out. As human beings we all know that it feels like something, from the inside. We have sensations, thoughts and feelings...We all know this, and it's central to being a human being, but for some reason, in the last 50 or 100 years science has tended to ignore this."
Patricia & Paul Churchland (treated as one mind, amusingly): Pat - "We don't know how neurons code information. That's a lot not to know." Sue objects that Pat has slipped from 'What's so special about consciousness' to "something we don't know about the brain". Pat responds: "Many people suppose that by sheer contemplation of a problem, they can tell whether it is hard or easy. This is self-deception, and usually self-aggrandising self-deception, to make it worse." Then..."People think that because we don't understand how consciousness is produced in brains, this must be telling us something really deep and interesting." She finds Chalmers distinction ridiculous. Paul cites examples of consciousness, like the difference between being awake and being asleep, and qualia (!), and says: "It's not clear how they knit together. It's not clear how the brain produces them."
Francis Crick: "[H]ow can you explain the redness of red in terms of physics and chemistry?"
Daniel Dennett: "[W]e have evolved a certain capacity for self-knowledge, a certain access to ourselves which gives us subjective experience - which gives us a way of looking out at the world from where we are. And this just turns out to be very hard to understand. How can something have that perspective?"
Susan Greenfield: "[I]t's a subjective phenomenon that we can't really define properly...it's very hard to know how to even frame the question as to how a subjective inner state is associated with something physical."
Richard Gregory: "[T]he huge gap between what qualia are like and what the physical system of the brain is like. In other words, how the hell does physics produce something which is so totally unphysical?"
Stuart Hameroff: "The brain is an excellent information processing system, but there's no accounting for how and why we have subjective experience, emotional feelings, an 'inner life'."
Christof Koch: "Well, the problem is to explain why sometimes I see something and sometimes I don't"
Stephen LaBerge: Not really asked directly, but he does say ""The problem to be explained is experience...".
Thomas Metzinger: "[C]onsciousness is opposed to all other states." Other states are only known from the outside. "Consciousness is different in that we gain knowledge about it from the inside as well as from the outside - and we don't really know what that statement actually means."
Kevin O'Regan: "A pseudo-problem." Then... " ...the problem is making the link between the experience and the brain process. And nobody seems to have found any reasonable physico-chemical mechanism that could make that link." He gives the move from vitalism as a comparison and says: "I think exactly the same paradigm shift could solve the problem that people call 'the hard problem of consciousness'."
Roger Penrose: "[T]here's nothing in our physical theory of what the universe is like which says anything about why some things should be conscious and other things not."
Vilayanur Ramachandram: "[A]ll the problems we have tackled and solved so far have to do with the external world...But we're now finally confronted with in some ways the biggest problem of all, namely, understanding the very organ that made all those other discoveries possible, turning on itself and asking, 'Who am I?'."
John Searle: Not asked directly, but says "[W]hat is the difference between the conscious brain and the unconscious brain?"
Petra Stoerig: "[W]hy does consciousness come about, what is it good for, how is it made?"
Francisco Varela: "There is the world, and there is me."
Max Velmans: "If you accept...that neural causal processes in the brain in a sense produce these experiences, and that indeed there might be neural correlates in the brain going on at the very same time as you're having those experiences, but that there is something deeply mysterious about the fact that these neural states seem to be completely different from these phenomenal worlds - then what kind of explanations would start to count as explanations of what is going on?"
Daniel Wegner: "[E]veryone has a consciousness but they have no access whatsoever to anyone else's."
Some fascinating thoughts. Many highlight the gap between first person and third person; some think it's not such a problem. What Penrose says is also a common theme, and close to how I've often puzzled over the problem; how do the cells in my brain produce this feeling but all the other cells in the universe not? Assuming that consciousness is limited to brains, of course. But Penrose goes too far, I think.