Most philosophers of mind (but not all) believe that rabbits have conscious experiences—that rabbits are not, as it were, mere machines all dark inside but rather that there's "something it's like" to be a rabbit, that they can have sensory experiences, that they can experience pain, that they have (in contemporary jargon) "phenomenology." After all, rabbits are not so different from us, biologically. Rabbits might lack language and higher forms of abstract and self-reflective cognition, but few philosophers think that such differences between us and them are sufficient to render rabbits nonconscious.
Most philosophers of mind (but not all) likewise believe that if we were visited by a highly intelligent naturally-evolved alien species—let's call them "Martians"—that alien species might possess a radically different biology from us and yet still have conscious experience. Outwardly, let's suppose, Martians look rather like humans; and also they behave rather like humans, despite their independent evolutionary origins. They visit us, learn English, and soon integrate into schools and corporations, maybe even marriages. They write philosophical treatises about consciousness and psychological treatises about their emotions and visual experiences. We will naturally, and it seems rightly, think of such Martians as genuinely conscious. Inside, though, they have not human-style neurons but rather complicated hydraulics or optical networks or the like. To think that such beings would necessarily be nonconscious zombies, simply because their biology is different from ours, seems weirdly chauvinistic in a vast universe in which complex systems, intelligently responsive to their environments, can and do presumably evolve myriad ways.
Okay, so how about Martian rabbits? Martian rabbits would be both biologically and behaviorally very different from you and me. But it seems hard to justify excluding them from the consciousness club, if we let in both Earthly rabbits and Martian schoolteachers. Right?
Ready for a weirder case? Martian Smartspiders, let's suppose, are just as intelligent and linguistically sophisticated as the Martian bipeds we love so well. In fact, we couldn't distinguish the two in a Turing Test. But the Smartspiders are morphologically very different from bipeds. Smartspiders have a central body that contains basic biological functions, but most of their cognitive processing is distributed among their 1000 legs (which evolved from jellyfish-like propulsion and manipulation tentacles). Information exchange among these thousand legs is fast, since in the Martian ecosystem peripheral nerves operate not by the slowish chemical-electrical processes we use but rather by shooting light through reflective capillaries (fiber optics), saving precious milliseconds of reaction time. Thus the 1000 distributed centers of cognitive processing can be as quickly and tightly informationally integrated as are different regions of our own brains—and the ultimate output is just as smart and linguistic as ours. If there were such Turing-Test-passing Martian Smartspiders, it seems we ought to let them into the bounds of genuinely conscious organisms, if we're letting in the bipedal Martians and the Martian rabbits.
