Hear me out. One of the inherent difficulties in analyzing consciousness (defined here as "what it's like to be something") is that there doesn't seem to be any way of accounting for it from a third-person perspective. In other words, there's no way to explain it scientifically, which is how we come to the best understanding of things. A famous thought experiment that illustrates this problem is that of philosophical zombies, or p-zombies, which are imagined creatures that are identical to human beings in every physical way except that they lack an experience of inner subjectivity - in other words, they exist unconsciously. Essentially they are sleep-walking all the time, yet remain perfectly functional in a way that is indistinguishable from a normal, conscious human. The question that arises from the thought experiment is: how do we know we're not living in a world of p-zombies, and extending from that, what criteria would we use to decide if this was a world of p-zombies or a world of conscious humans? As far as I know there's never been a compelling answer to this question. Sam Harris hosted the philosopher of mind David Chalmers on his podcast a while back, and Chalmers articulated an answer I hadn't heard before. Basically what he suggested (he didn't make this a formal argument or anything) was the unlikelihood that creatures that lack consciousness would sit around talking about it. He compared it to humans in a world lacking gravity talking about anti-gravity. The intuition is that without the experience of the initial concept, there wouldn't be any way of discussing places where it lacks. Now I suppose p-zombies could invent a concept like consciousness, rather than discovering or experiencing it. Importantly, all it would take is for that invention to happen a single time to throw the whole zombie world into philosophical chaos. One unconscious troll-zombie convinced that he really did have an inner experience of being himself could force the others to consider the same thing, and perhaps remain uncertain about the answer (we've got Dan Dennett doing something like the reverse of this in our world, professing that the experience of consciousness is a fake one). But I think I sit in agreement with Chalmers that discussing consciousness is a great example of something that could finally differentiate us from p-zombies. It's not the absolute solution, but it's something. Discuss.