Descartes tells us that the only thing we can be sure of is the fact that there exists some entity that is the thinker of this thought. The good news is that, of this we can be very sure. The bad news is that there is nothing and absolutely nothing else in the world that one can be sure of. This makes for a very binary world indeed. A world where we sit on an island of certainty in an infinite ocean of uncertainty.

So let’s assume that other human beings are just feigning consciousness and are actually just simulations, albeit quite vivid ones. They reproduce all the delicate nuances of social behaviour down to a tee. While talking to you, they demonstrate the existence of rich inner lives that reflect the totality of their life experiences. In as far as one can spot it, they display the existence of joy, sorrow, disbelief, hatred and all the other emotional states that one readily identifies in their own conscious lives. They may even report deep philosophical reflections on the nature of consciousness and some of them may even be professional philosophers of mind. One of them even has a name. He calls himself David Chalmers. David gives out all the signals that make you believe that he is conscious just like you are. Except David is just a vivid illusion and he’s just pretending to be conscious. For what nefarious ends he maintains this act is besides the point. All that matters is that there is nothing like how it feels to be David. In other words, if I could replace every atom of your brain and body with those of David’s then your lights would go out but you in your new avatar would continue to act like David. David is a zombie, albeit a chalming one.

When you confront David with your nagging doubts about his consciousness, far from being displeased, he chimes in with you. He says that if your speculations about his inherent zombieness were indeed correct, that would prove that consciousness didn’t necessarily arise out of cognitive/informational complexity. Even more damaging to your reductionist leanings would be his claim that his lack of consciousness proves that no amount of cognitive insight would bring you close to a possible explanation for consciousness because he possessed the same behavioural repertoire as you and yet you are conscious and he is not.