18 March 2013

The Hard Problem of Consciousness

Personally I find the phenomena of human consciousness to be a powerful evidence that there is more to reality than the physical material world that naturalism is selling to us. Following is an attempt to gather and articulate my reasoning.

What is the ‘hard problem of consciousness’

David Chalmers introduced ‘the hard problem of consciousness’ as the internal experience that we perceive. “It is undeniable that some organisms are subjects of experience… Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does.” Questions include: why do we experience colour, sound, emotions – as distinct from the physical questions of how we collect, transmit and process this information.

It is distinct from other problems of consciousness, which he calls the ‘easy problems’ (although non-trivial in themselves), such as creativity, learning, introspection, and so on. The hard problem focusses on experience – why we perceive anything at all. Whereas the other problems are all just about behaviours – the way the brain reacts to stimulus. They’re essentially just information processing problems: receive input, access memory, process, produce output.

The answer does not lie in physical matter

Clearly brains are made of atoms. A single atom has a (relatively) simple behaviour. Apply some stimulus, and it will exhibit a somewhat predictable result. Put a small number of atoms together and their limited behaviours combine to be collectively more complex. Exponentially. So it’s perfectly reasonable to expect that a brain-sized bag of atoms can exhibit behaviours at least as complex as the brain itself. But at the end of the day, actions within are still just like long causal chains of dominoes. Individual atoms are just reacting to the forces on them.

So what physical thing might be doing any sort of experiencing or perceiving? Physically, we still only have atoms. If a single atom has zero ability to experience, then neither does two or any number of atoms together. Regardless of how complex the structures, and how complex the behaviour, there is still nothing to do the perceiving.  If you have a whole stadium full of blind people, then corporately they still wouldn’t figure out whether the lights were on just by talking to each other. Chalmers suggests that maybe atoms do have their own simple experiential life - I'm far from convinced.

It should also be noted that the physical atoms – in the form of proteins and so on – that comprise the brain are being constantly refreshed, without apparent interruption to experience.

The answer does not lie in informational structures

It is often argued that experience must be an emergent property of the complex network of interconnected brain bits. However, I find this unconvincing. Informational systems still just produce behaviour. They can all still be distilled down to a Turing machine equivalent. (A Turing machine is the mathematical description of a computation process. Again: receive input, access memory, process, produce output.) Experience is not found at the logical level either.

A thought experiment: Physics tells us that only a finite amount of information can be packed into a space. What if we could capture a brain (or an entire person) into a set of bits. A complex algorithm could be devised to ‘simulate’ the brain on a Turing machine. It could then be converted to a universal Turing machine (bigger dataset, tiny algorithm). What are we left with: the entire logical structure of a functioning brain would just be a phenomenally long string of ones and zeros flipping on and off. It could still produce the same complex array of behaviours – but where is the ability to experience hiding in that string of bits? How does it perceive the colour blue?

A second: consider a constructed brain where it was possible to capture and log every logical input and output (along with its precise time and location) at each functional logical unit – as fine-grained as desired. Now rewire each functional unit so that it ignores its input and instead plays back from the log; and rerun it with the same stimulus. Every unit will give the same result as before, and present itself to the rest of the network in the same manner as before. It appears to run equivalently to the first run, even logically at the most granular level.  However, the entire execution is a fraud – just a play-back of a fixed stream of data, devoid of experience.

One question…

While we’re simulating brains, what might we get if we perfectly scanned and simulated a real brain? Would this demonstrate that experience derives from the physical? No. It may be observed to behave like the original brain, but we have no way of verifying if it is actually experiencing anything. After all, only the entity itself can be aware of its own experience. It may be what is often called a philosophical zombie – behaving, but not perceiving.

Natural or beyond

Whatever the solution to the hard problem may be, it is generally presented that the answer will be found without needing to invoke anything beyond the physical world that science is comfortable with. I find this to be circular reasoning. We are told that consciousness can be fully explained by the material world, because that is all there is. We are told that the physical world is all there is because we are not aware of any phenomena that cannot be explained by physical laws. Hmm.

To me, a much more satisfying answer is a dualist approach. The brain gathers information. It does a great amount of processing, and problem solving. But ultimately it has a non-physical element that is able to genuinely experience the data gathered by the brain. I call it a soul. But whatever it is, the problem is real, and I really don’t think it’s going to be solved with hand-waiving and a material reality alone. I’m not suggesting “we haven’t found an answer yet, so it is reasonable to appeal to the super natural”. Rather, I am arguing a case that there can be no answer in the natural alone.

The logical next question is ‘what good is an observing soul if it can’t influence the behaviour of the deterministic brain?’ That can be for another post.