In his blog entry “The Mystery of Consciousness II” Sam says:
The universe is filled with physical phenomena that appear devoid of consciousness. From the birth of stars and planets, to the early stages of cell division in a human embryo, the structures and processes we find in Nature seem to lack an inner life. At some point in the development of certain complex organisms, however, consciousness emerges. This miracle does not depend on a change of materials—for you and I are built of the same atoms as a fern or a ham sandwich. Rather, it must be a matter of organization. Arranging atoms in a certain way appears to bring consciousness into being. And this fact is among the deepest mysteries given to us to contemplate.
Many readers of my previous essay did not understand why the emergence of consciousness should pose a special problem to science. Every feature of the human mind and body emerges over the course development: Why is consciousness more perplexing than language or digestion? The problem, however, is that the distance between unconsciousness and consciousness must be traversed in a single stride, if traversed at all. Just as the appearance of something out of nothing cannot be explained by our saying that the first something was “very small,” the birth of consciousness is rendered no less mysterious by saying that the simplest minds have only a glimmer of it.
The word “consciousness” means different things to different people and it can hide the fact that someone is conflating many concepts within a single word. I think that Sam Harris and many in this forum are doing just that. I do not think he and others draw a distinction between the words experiences, sentience, and consciousness. I think this is a big mistake. I think that the concept of experiences is that most basic. Something “feels”. Those experiences may be pleasant, unpleasant, or neutral. While we may not think that an electron experiences or feels the electric and gravitational fields around it, it is not at all obvious to me that it cannot.
I think that the concept of sentience come after experience and is dependent on it. An organism is sentient if the detection of a state indicative of a decrease in the likelihood of its survival or reproduction generally leads to an experience of pain and detection of a state indicative of an increase in the likelihood of survival or reproduction generally leads to an experience of pleasure. While we may not think a starfish experiences pain when it is bitten, it is not obvious to me that it cannot.
I think that the concept of consciousness as it is generally interpreted is dependent on the concept of sentience. An organism possesses consciousness if it is sentient and its experiences encode abstracted information about its own state and the state of its surroundings. I think most of us will agree that humans experience much of the information we detect. We can even manipulate that information in our thoughts.
If we draw the distinctions I am suggesting, science could conceivably explain consciousness and sentience once it understood what kinds of things have experiences and the properties they possessed that are experiential. There could be degrees of sentience and consciousness that gradually evolve even if something more fundamental to an organism either experiences something or does not.