The idea of a philosophical zombie is the idea of a being that is just like a person in every functional respect but lacks subjective conscious experience. There is simply nothing it is like to be my zombie twin. Even if it is hard to see how such a being could exist, the mere logical coherence of the idea of a being that is functionally just like me but lacks consciousness tells us that subjective consciousness can’t be understood in terms of functionality. But analyzing mental states and processes in terms of functionality is the first step in cognitive science. With no associated functionality, we can’t then identify physical processes in the brain that realize that conscious experience. This makes it hard to explain conscious experience. This is what Chalmers calls the hard problem of consciousness.
Perhaps then science can’t explain consciousness. Chalmers thinks science can make progress if we accept mental properties like consciousness as basic elements of the world and give up on limiting ourselves to explanations purely in terms of physical properties.
However this works out, conscious experience remains philosophically significant. Imagine a world with no conscious beings in it. This is a place where nothing matters, simply because there is no consciousness anything could matter to. And this suggests that conscious experience is the seat of value. Things matter because they matter to someone. And things only matter to beings that are conscious.
Religious traditions seem to be onto this idea already. God is the conscious being that makes things matter in Christianity, Islam and Judaism. Perhaps our consciousness constitutes the spark of the Divine that we carry on these views. Even religious traditions like Buddhism or Taoism that don’t require a personal god recognize the ethical significance of conscious beings like us.
So, if we are looking for a metaphysical foundation for value, whether moral value, the value of love and community, meaning in life, or even the value of inquiry and understanding, conscious experience looks like fertile ground to explore.