Michael Hanlon reminds us of why human consciousness eludes our understanding:
The problem is that, even if we know what someone is thinking about, or what they are likely to do, we still don’t know what it’s like to be that person. Hemodynamic changes in your prefrontal cortex might tell me that you are looking at a painting of sunflowers, but then, if I thwacked your shin with a hammer, your screams would tell me you were in pain. Neither lets me know what pain or sunflowers feel like for you, or how those feelings come about. In fact, they don’t even tell us whether you really have feelings at all. One can imagine a creature behaving exactly like a human — walking, talking, running away from danger, mating and telling jokes — with absolutely no internal mental life. Such a creature would be, in the philosophical jargon, a zombie.
Why there’s no end in sight to the problem’s intransigence:
Nearly a quarter of a century ago, Daniel Dennett wrote that: ‘Human consciousness is just about the last surviving mystery.’ A few years later, [David] Chalmers added: ‘[It] may be the largest outstanding obstacle in our quest for a scientific understanding of the universe.’ They were right then and, despite the tremendous scientific advances since, they are still right today. I do not think that the evolutionary ‘explanations’ for consciousness that are currently doing the rounds are going to get us anywhere. These explanations do not address the hard problem itself, but merely the ‘easy’ problems that orbit it like a swarm of planets around a star. The hard problem’s fascination is that it has, to date, completely and utterly defeated science. Nothing else is like it. We know how genes work, we have (probably) found the Higgs Boson; but we understand the weather on Jupiter better than we understand what is going on in our own heads. This is remarkable.