The most interesting questions are those which our biases prevent us from ever asking, or knowing that they are questions which can be asked. Or sometimes questions are asked within the context of a worldview which causes us to miss the importance of question.
Why do we experience our thoughts and feelings?
We need not have evolved the ability to experience what our body senses, or to have any awareness of the thoughts and feelings which move through our brains. A camera, for example, does not experience the image which moves through its lens--nor does the film or CCD the image lands upon have any awareness of the image it captures.
If we build a robot it may have sensors for light, sound and pressure, a CPU to process the data gathered by the sensors, and a program to control the robot's actions in response to the sense-data it has collected. But at no point does the robot have any consciousness or awareness or experience of anything detected or of any decision-making it has done.
To be sure, there are plenty of people who will argue that such a robot must like us have some kind of experiencing mind, however rudimentary it might be. But I think it is clear that those people are either naive and inexperienced with robots or else mentally ill. Humans seem to have a biological propensity to see "mindfulness" even where it doesn't exist--thus ancients assumed beings in the sky throwing lightning bolts during thunderstorms or imagined angels moving the stars and planets along their appointed spheres. But once humans learn enough about storms and the solar system to explain their behavior without the assumption of consciousness, they forthrightly drop that assumption of consciousness. Today most of use should know enough about cameras, microphones, CPUs, software--the stuff of robots--to drop any assumption of robot consciousness.
A few people, oddly enough (apparently extrapolating from robots), go on to drop the assumption of consciousness in ourselves as well. Since it is difficult to assume a lack of experience with consciousness on the part of any human being old enough to form such an opinion, I find it difficult to avoid attributing such a viewpoint to anything other than feistiness or, again, mental illness.
If we adopt the obvious (and common sense) view that we humans do experience feelings and thoughts--and robots don't--then it becomes important to ask why we have experiences rather than not have them. Robots, of course, aren't biological beings. But it seems equally a matter of common sense to biologists that very rudimentary organisms--i.e., those which evolved first--also lack the ability to experience. For example, there is not likely to be experiences of touch without a central nervous system.
My first key point is this: we need to recognize that the ability to detect things touching us, the ability to detect sound waves and light waves, to detect molecules with receptors on our tongue, etc, need not have developed in concert with "consciousness" of the detection. There is no biological reason why we might not have evolved to be "blind" to our sense-detections: able like the robot to detect various things but also like the robot without any corresponding experiencing.
In fact, biologists know that our "experience" of light occurs not in the retina where the sensor cells are located but in the brain itself. Our direct sensing of photons, that is to say, is "blind" at the point on the retina where they are actually detected. What our sensor cells detect does not get turned into an experience of light until the data from those cells is collected by the brain which then turns around and creates a corresponding experience which we call light.
How the brain goes about creating our experiences is a mystery not easy to explain, but that our brain creates our experiences quite obvious. Damage to particular sections of the brain can warp (or even eliminate) the ability to have certain experiences, and the common sense explanation is that the brain is responsible for those experiences in the first place.
Beyond the very difficult matter of understanding how the brain goes about creating our experiences (or put another way, how the brain creates the mind) in the first place, is the question of why.
Why do we even have experiences? Were they necessary? If they were necessary, what made them so?
From a religious or philosophical perspective, of course, life would hardly seem worth much to us if we didn't have feelings and thoughts and sensual experiences. But I mean to ask the question particularly from an evolutionary perspective: why did experiencing evolve? It needs an explanation.
Teleological explanations won't be adequate because we are specifically looking for a naturalistic explanation, not a supernatural one. One can always postulate a God or "intelligent force" behind evolution, directing it along its way until one day, presto!--here we are with all of our wonderful (to us) human consciousness, grand pinnacle of the unfolded evolutionary plan.
That sort of explanation is easy--but also ad hoc, unprovable and ultimately unsatisfactory. It is unsatisfactory, it seems to me, because it throws the answer back onto a prior "intelligent force" or God without any way of explaining where that force or God itself came from or how it did its work. There is also something unsatisfactorily self-referential in explaining our intelligence/consciousness by saying that it sprang from some prior intelligence/consciousness--yet with a multi-billion year gap of evolution in between. Is it logically possible? I suppose so. But to me it is not satisfactory and certainly not sufficient, as far as explanations go.
The challenge then is to see if we can formulate a naturalistic explanation that is at least a bit more satisfactory and sufficient. That means it must be a non-teleological evolutionary explanation. It should not have any kind of pre-existing "intelligence" or "plan" built into it. There must not be a "purpose" behind it.
(Surprising as it may at first seem, postulating a "purpose" behind our existence deprives us of the full value of being alive. As a way to understand this, ask yourself what God's purpose is. For what purpose does God exist? I would submit that it demeans God to say that God exists for a purpose--it implies first of all that God was created by something else in order to fulfill the assigned purpose. To really be fully valuable and wonderful, God would need to be self-sufficient, self-contained, and not be programmed with a purpose. Likewise, for us to be fully valuable and wonderful, we would need to be the same.
This is why a non-teleological explanation--if we can find one that really works--is likely to be more satisfactory than a teleological one. If we can explain our intelligence, our experiencings, our consciousness without resorting to prior intelligence, experiencings or consciousness then we will have found a more satisfying explanation for our existence. Not that existence itself can ever be explained--we should certainly hope that it is ultimately unexplainable for these same reasons.
My interpretation of evolution is non-teleological, very much along the lines advocated by Stephen J. Gould. There is no goal or built-in direction to evolution--nor does evolution "favor" one trait over another or fitness over non-fitness. Evolution, as I see it, does not "choose" or "validate". It does not even indicate the "superiority" of one species over another. It is not all about "the selfish gene", nor is evolution biased toward biological fitness.
Humans have a tendency to map "purpose" onto evolution when it simply isn't there. What is there is this: some species have more offspring over the long term than other species with the result that over time lines of offspring from some species continues on while lines from other species may disappear. At certain points we declare that "speciation" has occurred and a new species evolved into existence, etc. My point here is that there are no underlying guiding principles or rules. There is no basis on which to declare that individuals whose offspring died out (or who had no offpring, etc) were less valuable or less successful than those whose offspring went on to thrive and "speciate"--and this is because the basis of any such judgment can only come from us and our personal preferences and biases. In a naturalistic, non-teleological universe, there can be no built in basis for value judgments.
Having completed that tangent, it is time to focus on a non-teleological evolutionary explanation--I should say plausible explanation--for the biological development of consciousness (or in my preferred terminology, experiencing.) The explanation need only be plausible because the question we want to answer is whether satisfactory biological explanations are in fact possible at all. I am not looking, that is to say, for a full-fledged scientific theory--that is best left for evolutionary biologists to handle.
What I instead want to know is whether purely biological explanations can be coherent. Whether they can truly be more satisfactory than teleological explanations of our existence. Whether they can "work" both intellectually and emotionally to explain why we are the way we are.
I think they can, as we will see as we continue to ramble toward our goal.
But I have to stop rambling for the moment -- time to eat.