The problem of consciousness comes to be a problem due to certain core assumptions that we are inclined to make. Namely, we are inclined to presume that all physical events have physical causes. We are inclined to say that physics is complete. We say there is causal closure in the physical realm.
Yet we have this concept of qualia which explains in non-transparent terms what it's like to have experiences. Qualia is what it's like to be a first-person, or to have that point of view. Everything that has a first-person point of view has qualia. And if it doesn't, while appearing to, it is called a zombie. (That was a very behaviorist way of explaining that.) In other words, zombies are said to at least have psychological consciousness, while at the same time having no phenomenal consciousness. The phenomenal is the first person point of view. So, there is no way of experiencing "what it's like to be a zombie" since there is nothing to experience when being a zombie.
Zombies are juxtaposed with physically-identical entities that are like the zombie in every way except that they have phenomenal consciousness. That poses an apparent problem. The mere conceivability of zombies is said to make zombies possible. And if zombies are possible, then that means there is something else, non-physical stuff, which separates zombies from non-zombies.
But this view is wrong on several accounts. I'm not going to explain what follows in detail here. I am only going to offer some of my ideas that I want to come back to later. I'm gathering a list of reasons as to why that view is false.
- Proper concepts -- like the "married bachelor" (a contradiction) one can still be asked a loaded question and imagine some scenario where bachelors -- who call themselves that -- live in a bachelor pad and do bachelor activities and are somehow, however ambiguously, married. This is because the concepts are not properly defined. There would be no such thing as a married bachelor. This is a language problem.
- Behaviorism -- on a behavioral account, which is not the best hypothesis to use (not never, but most of the time) if it acts like it has phenomenal consciousness, then it has phenomenal consciousness. We don't have first person access to the zombie mind, so there's no way to tell regardless.
- Explanatory gap -- there is in general a gap between explaining how the mind causes the body to work. If that same gap exists even in bodies that have phenomenal consciousness, it is expected to exist (or not exist?) in bodies that do not have it.
- Humean non-casuality -- one could deny that causation is itself physical. "Cause" and "effect" are not physical things. They are concepts. The idea that two physically-identical entities would cause different styles of consciousness does not pose a problem if there is no underlying causal problem.
- The conceivability/possibility distinction is one that was fabricated in the Kripke framework. It does not entail the possibility of non-phenomenal consciousness in our own possible world. (That's a weak objection because they're still possible in other worlds.)
- Eliminativism -- why accept that qualia is a good explanation for first-person mental states? If one takes the view that qualia is a philosopher's distinction, and that what is really going on are neural networks and c-fibers firing, then qualia is just a fancy word for neural patterns and networks. It would be easy to then deny that the possibility of non-phenomenal consciousness exists, because that state is brought about by strict neural laws.
- Emergentism -- there are different levels of consciousness. Low-level processes, when in the right order, will give rise to higher-level processes. If a zombie is physically identical to something else that has phenomenal consciousness, then all the processing levels would be the same, including the processes that give rise to phenomenal consciousness. So in a zombie, some of that criteria would not have been met, and thus they are not physically identical.