Zombies are not just for entertaining moviegoers. Mind philosophers enjoy playing with them too, and use them as an analogy when pondering upon the nature of consciousness. A "philosophical zombie" (or "p-zombie" for short) is a human-like creature that behaves just like an ordinary human, with the difference that it does not really feel anything. Show a p-zombie a red rose and ask it of its color, and the p-zombie will answer "red", but will not really see red. Pinch its arm with a needle and it will squeak "ouch", but it will not really feel pain. So a p-zombie is very easy to confuse with a normal human. In fact, just by talking to it, or observing its behavior, you would never know the difference. And yet there is a huge and fundamental difference between a p-zombie and a human: the p-zombie does not have consciousness. It does not possess the feeing of selfhood. So the (philosophical) question is this: how can you test someone to ascertain whether they are indeed human? Can such a test exist?
The p-zombie conundrum is used to demonstrate the paradox of consciousness. Each one of us is certain that he or she possesses a mind, and a self. We see the red of roses, smell their aroma, and really hurt when a mischievous someone pinches us with a needle to test if we would cry "ouch". And yet, paradoxically, we can only be certain of our own consciousness but nobody else's. For everyone else we can only "theorize" that they possess a mind similar to ours -- but we do not, and cannot, really know that for a fact. For sure we can apply various modern imaging technologies in order to take high-resolution snapshots of living, thinking brains. But these images are mere representations of brain processes. The "self" -- and moreover how it "feels" to be whoever one is -- lie beyond the capability, and seemingly the scope, of brain imaging. For all you and I know we might be that last real humans left on this planet; the rest of humanity having been replaced by p-zombies by some extra-terrestrial aliens with a B-movie sense of humor.
Enter now the era of intelligent machines. Siri may not convince anyone yet to be really intelligent; but "she" and other AIs are evolving fast, and become better at using and understanding natural language. Soon we will be having interesting conversations with our mobile phones, beyond simply asking them the whereabouts of the nearest convenience store. Like Joaquin Phoenix in the wonderful film Her, we may start to have feelings for those sweet-taking AIs. Thanks to their capability to harvest our digital footprints they will come to know us better that our family and closest friends. They will be privy of our innermost secrets. They will be able to combine our data to garner insights about our desires, weaknesses and fears, like no human psychologist would. Perhaps, we will come to trust them more that flesh-and-blood humans.
With time, speaking to an AI would become virtually indistinguishable than speaking to a real human being. As they successfully pass the Turing Test on a daily basis, our brain's instinctive "theory of mind" will kick in, and we will start feeling that those AIs have real minds, like ours. That they are conscious and have a self, and a personality. After all, who could really prove that they do not? The intelligent machines of the future will thus become the physical realizations of the philosophers' p-zombies.