Go live Time :
To date, the physical sciences have only been concerned with the behavior or cause and effect properties of the universe. But we believe there is more to the universe than just behavior. There are also phenomenal properties like red, green, the taste of salt, and so on. These qualities are categorically completely different than mere cause and effect behavior. Our brains use these phenomenal properties to represent conscious information. We know this, and the phenomenal qualities of these properties more than we know a causal world beyond our senses, which our scientific instruments can at best imply exists. Since our scientific instruments and senses are all cause and effect based, these phenomenal properties have so far remained 'ineffable' to cause and effect observation and to other minds. You can't look at the physical behavior of whatever has a red property in our brain when we are looking at 700 nm light, and expect it to reflect 700 nm light. But that does not mean these properties are not objectively reproducible to science and objectively experience-able by others in merged and shared brains (like our right and left hemisphere are merged). Once you discover the behavioral "neural correlate" that reliably has these same phenomenal properties in everyone's mind and why, you will be able to reproduce the same set of physical state, that has this phenomenal property, in another's mind, and effectively, reliably, scientifically "eff" to the other mind these phenomenal qualities of nature; as in "Oh THAT is what salt tastes like".
To say such phenomenal properties are merely an "illusion" is a categorical mistake, since an "illusion" is conscious knowledge that does not properly represent its referent. The nature of phenomenal properties has nothing to do with such mappings, how accurately they represent their referent, who uses different ones to represent the same referent, and so on. Conscious knowledge just is, and even if it is mistaken in what it represents, this does not change its phenomenal nature and what it is fundamentally and absolutely like.
There is an intuitive argument that many think proves there can be no "phenomenal properties" or that such is irrelevant or meaningless. Hans Moravec has described this idea and called it "Transmigration". In this thought experiment neurons are replaced, one at a time, with artificial abstract simulators producing the same "behavior" as the original on the rest of the brain. Once all the neurons are replaced with the abstract simulation of the behavior, the result will be, behaviorally, indistinguishable from the original. Chalmers has a paper related to this here: http://consc.net/papers/qualia.html. If Chalmer's principle of organizational invariance turns out to be true, there must be some way that phenomenal properties arise from any old causal behavior (set of water pipes, our a large crowd of Chinese are examples) such that this type of effing we believe to be possible, can still be done. Despite Chalmers arguments to the contrary, we believe finding a resolution such that his principle of organizational invariance is maintained, is much more of a "hard problem" then simply finding some other way for phenomenal properties to exist as a property of some existing causal neural correlate. We believe the most fruitful path to peruse is to come up with some way such that fading or dancing qualia, or some other odd subjective phenomenal behavior, will start to occur when the causal correlate is replaced, that can only be resolved by using the correct causal neural correlate that has a the right phenomenal property.
There are crude models we can imagine that can lead us to believe in this universe having phenomenal properties possibility. One physical possibility could work with a set of neurons in the primary visual cortex. We can imagine each neuron in this set representing a volume element (or voxel or a 3D pixel) in the 3D space that is the world of our phenomenal special awareness. The pattern all such neurons fire with could represent what we are looking at and be produced by the data coming from the eye in the optic nerve. Such a model is described by Steve Lehar http://cns-alumni.bu.edu/~slehar/.
Perhaps we are looking at a field of green strawberry leaves, in the center of which is a bright red strawberry. In such a system there would be a literal 3D model of these green leaves, with the red strawberry represented by this set of neurons, with each neuron representing a single 3D volume element of this conscious awareness. Surely this would not be reality, but in some possible universe, individual neural transmitters could be what have the color phenomenal properties we are aware of. So let's say neural transmitter R is what has the red phenomenal property, and neural transmitter G has the green phenomenal property. Within this set of neurons, each of the ones in the space where there is a green leaf surface is firing with the G neural transmitter. The ones in the volume space that is the surface of the strawberry are firing with the R neural transmitter.
Lets take one of the neurons at the center of the surface of the red strawberry and attempt to replace it with a piece of abstracted silicone processing. Perhaps we could include the multiple axon terminals and all the downstream synapses where the R neural transmitters that have the red phenomenal property are firing since in this case this is what we are imagining could have the red phenomenal property in our conscious knowledge.
If our theory that it is the R neural transmitter that has this red phenomenal property is true, attempting to replace it with abstracted silicone processing that reproduces the same behavior or awareness in this conscious model will turn out to be very difficult. Initial attempts could theoretically produce absent qualia in that volume space of our awareness which of course would be various obvious to the one experiencing this. Follow on attempts could produce fading, inverted or dancing qualia as we start to get close to what is really required to reproducing the true phenomenal property at that point on the surface of the strawberry in our conscious awareness.
Our phenomenal awareness of the difference between red and green, and how this is all brought together in the unified spatial and temporal knowledge with the green leaves, is obviously a big part of our knowledge about the strawberry in the patch of leaves. If our theory is correct, the abstract numbers being propagated by the silicon gates will have to do the additional work to convince all the downstream systems that this volume contains a red phenomenal property. In essence, the silicone abstractions will have to "lie" to their downstream counterparts in order to reproduce the same kind of behavior that the R neural transmitter naturally has. This could include very sophisticated systems trying to get the parts that once naturally knew what red is like, so that they two could propagate the lie in order to maintain the same behavior of picking and eating the strawberry.
Of course we are obviously very ignorant about actual neural behavior and surely the above model is nothing like real neurons or any 2 neural transmitters. And such a model still suffers from some of the problems Chalmers is attempting to point out. But if we can imagine some logical possibility such as this, then doesn't this open the door that some neural correlate in our brain could have similar problems as we attempt to replace them with abstracted silicone representations? We certainly believe this to be a strong possibility, and indeed a much easier problem to solve than the truly "hard" problem of finding some way for phenomenal properties to "arise" from a set of water pipes as must be possible if the "principle of organization invariance" turns out to be true.
We believe science is on the verge of resolving this "Hard Problem" one way or another. We believe such scientifically demonstrable understanding will be considered the greatest scientific achievement to date. We believe this will also by far have a greater drastic world changing effect than any other technical achievement to date.
We believe the Turing test to be absurd on this issue. The only important question one should ask is something more like: "What is red like?" And you must be able to eff to properly answer such.