Philosophers of mind talk a lot about zombies. I want to introduce a related species of philosophical monster, which I shall call jekylls. Like zombies, jekylls are atom-for-atom duplicates of us, inhabiting a world with the same physical laws as ours — a world which, let’s assume, is causally closed. Your jekyll twin has all the same physical and functional states you do, including mental ones. It has the same functionally defined perceptions, sensations, thoughts, desires, memories, and emotions, and it is conscious in a functional way too. It also has a sense of self, built of memories, emotions, and introspective and interoceptive states — all functionally defined. (For simplicity, I’ll use ‘psychological’ as David Chalmers does in TCM to mean ‘psychological in a functional sense’.) So far, then, jekylls are just like zombies. There is a difference, however. Jekylls also have phenomenal states, understood as qualitative mental states that […]

Panpsychism is the idea that basic physical entities are essentially micro-consciousnesses and that our macro-consciousnesses result from combining the phenomenal natures of the physical entities that constitute us. The view faces the combination problem: how do simple, discrete micro-consciousnesses combine to produce complex, unified macro-consciousnesses? This problem has been much discussed, but there’s an aspect of it that has, I think, been relatively neglected. Here it is. It looks like a sensible methodological assumption that if two entities are qualitatively identical from a physical point of view, then they are phenomenally identical too. If panpsychists don’t make this assumption, then it’s hard to see how they could construct anything like a science of consciousness. If panpsychism is true, then we are acquainted with only a tiny fraction of phenomenal reality — the portions that constitute our consciousnesses. The rest can be known only indirectly, by inference from corresponding physical features. […]