A Very Simple Argument Against Any General Theory of Consciousness
Suspiciously simple, you might think. Here it goes:
(1.) No general theory of consciousness can be justified except on the grounds that it gets it right about certain facts known independently of that theory. Those facts include facts about the presence or absence of conscious experience in a wide variety of actual and possible beings that are unlike us in potentialy relevant respects -- beings like frogs, insects, weird sea life, computers and robots of various types, alien beings of various types, and collective superorganisms of various types.
(2.) Independently of a well-justified theory of consciousness, we cannot know, with regard to most such beings, whether consciousness is present or absent.
(3.) Therefore, no general theory of consciousness can be justified.
Are ants conscious? Block's Chinese Nation? Star Trek's shipboard computer? People will reach different intuitive judgments (as philosophical discussion amply shows) -- and there's no particular reason to think, anyway, that our intuitive judgments should track the truth about such matters. It seems that a well justified answer to these questions must lean on a well justified general theory of consciousness. But there are a lot of (actual and potential) general theories of consciousness, some of which imply that consciousness is very widespread, others of which imply that consciousness is relatively rare. We cannot choose among those theories without prior knowledge of how widespread consciousness in fact is -- the very knowledge that we cannot have without such a theory in hand.
It's a tight little vicious circle.