This is really my attempt at approaching eliminative materialism, and probably reading Paul Churchland or Daniel Dennett's papers would be better for you to get the point. I'm just writing to organize my thoughts.
There are three big problems in science: universe, life, and consciousness. There is a good theory of the universe on the macro and micro scale, and the problem of its origin. They are not the final word, but we have a good sense of any future updated theories would be like: mechanistic, mathematical, probably using real, complex, and discrete numbers.
A theory of life is still in the works, though there are encouraging attempts. The physical construction of life and the descriptive theory of life is now complete except in the details. We know that it would be something made of evolution, thermodynamics, chemistry, and of course, mathematics. The engineering theory of life is still greatly missing. We do not know how to create life, at most we can fork the genetic code and do little modifications and mixings. We don't even know if a robot is alive.
A theory of consciousness is in an even earlier stage. There are some basic studies of the description of consciousness, and there are dozens of hazy philosophical theories that needs to be made quantitative using future data.
One problem with consciousness is its paradoxical qualities, creating questions that seem to both be compelling and deformed:
- "Why am I me instead of someone else?"
- "If Pinkie is copied, which one is the real Pinkie?"
- "Is the feeling of blue same for everyone?"
- "How does one freely choose?"
Now compare them with analogous questions from universe and life:
- "Why is this rock this rock instead of that rock?"
- "If this book is copied, which one is the real book?"
- "Is this website the same website on every computer?"
- "How does a slime mold decide which way to go?"
The analogous questions lose their mystery and becomes mundane, confused, or fascinating but also scientifically analyzable.
Possibly the problem is with the understanding of conscious itself, which is too confused. I propose to remove consciousness from explanations of life behavior (human or not) as much as possible. If it can be fully removed, then the problem of consciousness is solved. If it can't be fully removed, then it concentrates the effort for solution.
As a sketch of how such a removal might be done, consider a fully physical explanation of how humans talk, which is currently infested with consciousness. The standard account is that there is a consciousness that feels something, then formulates that into words and sentences, then expresses them. Unconscious speaking is considered nonsense, meaningless, noise. This doesn't have to be.
The Heptapods from Story of Your Life (Ted Chiang, 1998) are an example of a "free-will-free" form of life. Their language has determinism baked into it, just as human language has free will baked into it.
What kind of universe could produce two kinds of life such that one is deterministic in language, but the other is free in language? And in such proximity too, such that they can actually meet each other and share the same physical space and physical laws?
To answer such questions in a physics way, one would use a physics of language. What is a language according to a physicist?
What is a deterministic language, and what is a free-will language? How would a description of free-will emerge in a deterministic system such as our universe? And most importantly, how does a universal language, a symbolic system that can models the physical world that it is in, emerge in a deterministic world?
This is analogous to the problem of zombie language: I once read that in a world with only philosophical zombie humans, human languages would probably have not evolved to talk about consciousness and inner experiences because there is no such nonexistent thing. This argument is dumb, since human languages already talk about many nonexistent things, but it points at an interesting question: how would a deterministic system evolve a language that talks about things happening in it?
Physical self-referential science
In the same spirit, what kind of deterministic universe would have little bundles of matter inside of it that behaves roughly the same as some other patches of this universe? We call these little bundles of matter "computers running physical simulations", or "a human brain thinking about science", or maybe even "a lion brain thinking about which way an antelope is probably going to go next".
If such explanations can be done in detail, that would be a self-reference in physics: a physical system (our universe) containing a substantial description of itself (the explanation), as well as an account for why it is likely for the description to exist in the first place (the explanation about why a physical world is likely to contain its own description).