The Hard Problem Biology Will Never Solve
On the explanatory gap between biology and conscious experience
Modern biology explains the mechanisms of perception and cognition in increasing detail. We know how the eye detects wavelengths, how neurons transmit signals, and how brain activity correlates with thought and emotion. But none of this explains the central question: why any of it is accompanied by conscious experience at all.
Biology can explain much of our behavior as a social animal. The hard problem is explaining qualia, or subjective experience itself. The redness of red. The feeling of falling in love. The taste of coffee, the stab of a pain. These states are associated with physical processes in the brain, yet it remains unclear why any such processes are accompanied by experience at all.
Another way to consider this issue is to imagine a machine combining cameras, LiDAR imaging, memory storage, and modern artificial intelligence into a unified system capable of constructing a detailed model of the external world. It could distinguish colors, navigate environments, recognize human faces, and verbally describe objects with human accuracy. Yet despite all this information processing, we would still have no reason to believe the machine experiences the redness of red or the feeling of perception itself.
Humans also process information mechanically, at least biologically speaking. Our eyes detect wavelengths, neurons transmit signals, and the brain categorizes sensory data. Yet unlike the camera, we possess subjective experience. We do not just merely register red, we experience the redness of it.
Imagine a possible being that is biologically human, responds to stimuli, and behaves in every way as we do. They laugh, cry, fall in love, write poetry, and have favorite foods. But this being has no subjective experience, there is nothing that it is like to be them. These are reffered to as philosophical zombies. The point is not that philosophical zombies could exist in reality, but that consciousness appears conceptually separable from purely mechanistic explanation.
Some argue that future neuroscience will eventually close this gap completely. I believe this is extremely unlikely. Even a complete account of brain structure and activity would still be a description of mechanisms, correlations, and observable behavior. Biology may continue uncovering increasingly precise relationships between brain states and conscious states, and it may fully explain the neural basis of emotion, memory, and perception. Yet none of this appears to explain why these processes are accompanied by subjective experience rather than occurring unconsciously like information processing inside a machine.
These considerations may be worth incorporating into our broader approach to the study of the mind. I remain open to our many differing explanations of subjective reality, but a purely physical description of the brain and its processes will only account for structure, function, and behavior, and yet not clearly capture subjective, qualia-filled experience itself. The question is not only how the brain processes the world, but what kind of thing reality must be for those processes to feel like anything at all.