There is debate concerning our ability to know the nature of alien consciousness, but there is no debate concerning our ability to know the nature of our own consciousness. It is argued that we can’t know what it is like to be a bat, but accepted that we can know what it is like to be a human, since human is what we are. Similarly, it is doubted that a blind person can know what it is like to see, but it is not doubted that a seeing person can know what it is like to see. Some maintain, to the contrary, that it is possible to grasp the nature of a consciousness that one does not have: but no one questions whether we can know the consciousness we do have—we assuredly know what thatconsciousness is like. The thought is that one knows consciousness from one’s own case, so of course we know what it is like to be us. I know what it is like to be a normal conscious human since I am one, though it is doubtful that I can grasp other types of consciousness. But is this really so obvious—do I unerringly grasp what is like to be me? Do I occupy such a privileged position with respect to knowing my own phenomenology? Do I, for example, really know what it is like to see? Do I know what it is like to see red, say? Is this alleged knowledge infallible, complete, and unassailable? Is the character of my consciousness transparent to me?
Does a bat know what it is like to be a bat? The answer is surely not: the bat has echolocation experiences but it doesn’t have knowledge of those experiences. It doesn’t have the kind of reflective introspective knowledge that we have of our experiences. It doesn’t have concepts of its experiences, though it has the experiences. Certainly bats have no words for their experiences. There is something it is like to be a bat but bats don’t know what that is (no true justified belief about it). Generalizing, animals don’t tend to know what it’s like to be them, though there is something it’s like. Maybe our close primate cousins know what it’s like to be them, but if so they are the exception in the animal kingdom. I wouldn’t be at all surprised if we are the only animals on earth that know what is like to be themselves: only we have the cognitive sophistication necessary to form concepts of our own experiences, and hence have the phenomenological knowledge that we have (as we suppose). That kind of knowledge is by no means an automatic consequence of possessing the experience; it is not a package deal. The fact is one thing; knowledge of it is another. Phenomenological knowledge is superimposed on phenomenology not written into it. Seen from this perspective, it is surprising that we have the kind of phenomenological knowledge we have (or seem to have)—shouldn’t we be as ignorant of our phenomenology as other animals are of theirs? Why then do we uncritically assume that our phenomenological knowledge is so inerrant? Phenomenology is quite hard to know, if other animals are anything to go by, so why assume that we have it down pat? We are pretty bad at grasping the phenomenology of other species, so why assume we are so brilliant at grasping our own?
You might reply that we have an introspective faculty and they don’t. That is undoubtedly true, but it doesn’t answer the question: for how does this faculty generate the knowledge in question? Philosophers have spoken of “knowledge by acquaintance”, but no explanation is given of how this works exactly. The thought appears to be that we perceive our own conscious states with the introspective faculty and then somehow derive the concepts and accompanying knowledge from this perception. But perception alone is neither necessary nor sufficient for knowledge, and anyway this whole story is notoriously rickety. What is this “derivation”—is it some kind of “abstraction” in the manner of Locke and Hume? And why should it yield the kind of fullness and infallibility that we tend to ascribe to our phenomenological knowledge? Isn’t it possible that our self-knowledge in this respect should be partial, fallible, superficial, and erroneous? Why should the phenomenological facts be transparently given to us? No doubt the phenomenology evolved first, so why should the later cognitive ability perfectly match the facts it seeks to represent? Maybe the facts exceed what we can know of them, so that we don’t fully grasp even what it is like to see red. Or maybe we misattribute qualities to our experience that they don’t really have. Maybe we only imperfectly grasp what it’s like to be us. Just as we might know more about bat experience than the bat, given its limited cognitive abilities, so a possible being might know more about our experience than we do, given our cognitive limitations. We are certainly not too impressive at saying what it’s like to be us. We can’t put it into words. Our so-called knowledge seems notably inarticulate, purely ostensive, and suspiciously private. Maybe a superior being would disdainfully remark, “Those humans have no idea what it’s like to be a human!”—just as we say the same about bats. A skeptic might even insist that we could be completely wrong about our phenomenology, stressing the distinction between phenomenological facts and knowledge of those facts. So we can’t just assumethat we are omniscient with respect to what it’s like to be us. A human child presumably undergoes a transition from merely possessing a phenomenology to knowing that it does, and it is not to be supposed that this is a move from complete ignorance to complete knowledge; more likely, it is piecemeal and partial, possibly flawed. Curiously, though, it strikes us that we have a kind of godlike insight into our phenomenological make-up, whereas we have no such insight into our bodily make-up. But that would be peculiar given the nature of the facts and our generally feeble grasp of phenomenology (even those little bats defeat us!). When God looks into our visual consciousness he might see there a lot more than is evident to us, with blind spots and areas of error, or even wholesale ignorance. We have some idea of what it’s like to be us, as perhaps chimps have some idea of what it’s like to be them, but that is not to say that we have the kind of superior penetrating knowledge that we tend to assume. For example, there might be phenomenological similarities between vision and hearing that we are oblivious to (as the case of bats would suggest). Or maybe perceptions of shape and color are more distinct than our phenomenological knowledge indicates: what it is like to see the two might be more disparate than we suppose (their difference of objectivity might be clearly etched into the phenomenology). At the extreme a skeptic could hold out the possibility that we are quite wrong about what it’s like to be us—maybe we are much more like bats than we suppose! Maybe our visual experience is not really as we believe it to be. It is not that we are wrong to make the self-ascriptions that we do—we really do see red and feel pain—but when it comes to grasping the natureof our experience our knowledge might be quite defective. If so, our self-knowledge is closer to our knowledge of others than we uncritically suppose: we partially grasp the nature of bat experience but we also only partially grasp the nature of our own experience. It is not that we are totally inept in the alien case but magically flawless in the home case; it is more a matter of degree. If our introspective eye could be magnified tenfold, we might be surprised at how our phenomenology looks: it might look a lot richer and stranger than it does now. It might indeed strike us as undeniably alien.
Suppose we came to the conclusion that we don’t know what it’s like to be us—to see, hear, smell, taste, feel, etc. We could then argue that our consciousness can’t be reduced to the brain because we have no such cognitive limitation with respect to the brain: our ignorance of our phenomenology is not matched by our ignorance of the brain. This would be an anti-materialist argument of the same form as the classic bat argument, but without the bats. If we can’t know what it’s like to be us but we can know all about our brain, then facts about what it’s like can’t be facts about the brain. We would be more ignorant of our phenomenology than materialism can explain.
 We could call this the “ignorance argument”: just as we are more ignorant of a bat’s mind than materialism can explain, given that we can have complete knowledge of a bat’s brain, so we might be more ignorant of our own mind than materialism can explain, given that we can have complete knowledge of our brain. This provides a new twist to a familiar line of thought.