Will it ever be possible to replace the human mind with all its functions with a machine, even the most sophisticated, such as consciousness? My answer is definitely no, although many people, including some distinguished scientists, argue that one day this may be possible. This day, despite whatever the greatest of optimists and in spite of the speed of scientific progress, will never happen in my opinion and this is why.
Mind uploading could (I emphasize could) emulate the brain in its entirety and therefore with all its biological and functional substrate. To work, this technique should involve all the mapping of our brain and of all other animals to match the level of a computer. In the latter case, since animals have a less complex brain than ours, the process should be easier to emulate. Theoretically this is true and therefore it may be possible one day to build a machine that replaces our mind, including consciousness, but, I repeat, in reality this will never happen.
In practice one should not even ask oneself to solve the problem, because it is an impossible dilemma, at least as far as consciousness is concerned. On the other hand, even our brain has an incomplete understanding of this natural function itself. Indeed, the brain is responsible for all our mental functions, some of them we know a lot about and we have even measured them, such as sensations, but as far as consciousness is concerned, we still know very little. What we do know is that consciousness probably evolved like any other psychological function and it puts us in a position to face life much better, at least from a sociable point of view and therefore relational. Without consciousness we could not have developed such a complex human society and extended to all humanity, something animals are not completely capable of. With consciousness we could evolve a higher-order thought and thus become beings with advanced metacognitive abilities and thus reflect on our thinking or think about thought. We could not have evolved a high-level integrative capacity of all the information that comes to us from the outside world and also from our body. But for information we must not fall into the trap of thinking that the integrated information system of our brain works like a computer.
In humans and animal, the information flows through neurons, meaning through biological material, while in a computer nothing flows as such, in it there is no biological material and there is a substantial difference between our brain and a computer. Artificial neural networks obviously exist, but they are not and will never work like those of the brain. Someone might ask what does it matter if a network is artificial or natural when with the artificial ones we can solve many problems that control our life? The answer is that this could apply to very simple functions of our brain that we need for example to experience sensations or emotions, but never to replace them with consciousness.
What does consciousness possess, to be so particular and different from all other psychological functions?
There is no simple answer to this question, because consciousness has yet to be scientifically designed. Very advanced results have been achieved with regard to functions without which consciousness would not exist, such as perception and attention, but nothing truly scientifically based entirely on consciousness. There are, for example, many models, although exemplified on how the brain selects attentional information and how it processes it, this we refer to as attention pattern, but we don’t yet know how this information is then implemented in consciousness. Attention is a filtering system and focuses on developing a cognitive process of an attentional type, but we still don’t know how well this system is integrated with language or memory or indeed, other functions. Attention implies a consciousness, this is true, but it is not of an overall and subjective consciousness.
Why a computer can never replace our consciousness
The idea, that a computer can never replace our consciousness, is not only the result of philosophical or metaphysical studies, but practically it is numerical. This means that in theory one day a machine can be built and replace all the activity of our brain, but in practice this will never be numerically possible. A computer can recognize, as we know, a human face and identify it, but the computer can never know what a face is. A computer can never possess a theory of mind and therefore attribute to other individuals of the same species but also of different species a state of consciousness. A computer, as we know, can emit words in all languages and therefore can theoretically speak, but it will never know what an articulated language is. A computer can never be aware of what it sees in the first place and what it says in the second place. As for the practical and therefore numerical question, let's see why a computer, however large, sophisticated and powerful, can never possess a consciousness. The human brain is composed of a total of about 100 billion nerve cells including those of the cerebellum. Each neuron can communicate with other neurons through a number of synapses that can range from one thousand to 10 thousand (103) (downwards). Theoretically a neuron can communicate with the other hundred billion neurons, minus one. If we reason in numerical terms and therefore that a neuron operates according to a binary system (1/0), being the number of neurons of the order of 1011 (11 stands precisely for 100 billion), the possible nervous states will be of the order of 2 elevated to the 10th power and all elevated to the 11th power, ultimately 2 elevated to the 14th power. This is an impossible number even to imagine (one hundred trillion) and a computer, however infinitively large, would be unable to read, and therefore never be able to elaborate such a complex information network.
A man would need several lives to count one at a time all these nervous states, for a computer it would be at least difficult or even impossible. We have to keep in mind that a neuron does not work as an information bit (open/closed or 1/0), but it is something much more complex and therefore the base would no longer be 2 but who knows what other number: it could be a thousand, ten thousand or a hundred thousand. If this is the case, it is better to let it go and to continue to break up the consciousness (as it is doing now), but only for our convenience, for instance, in attentional consciousness, body consciousness, vision consciousness etc., but never in its entirety. It is obvious that in a brain not all synapses are active, that they are all excitatory and intense, moreover the connections between neurons can be modified over time as well as the pattern of its connections (moreover, for example, we do not yet know the function of glial cells) in substance you can never reach the essence of an individual who owns a normal and efficient brain. The mind of an individual can therefore never be simulated with a machine or an entire computer. The blunder perhaps stems from the fact that when the human genome was discovered and totally identified, it was similarly thought that this could be done for consciousness.
The fact is that the number of genes that make up our DNA is infinitely smaller than the nervous states that characterize a human brain. To study the brain you can map some of its parts, but it would be impossible to do it for the whole brain. It will be possible to scan some parts of it, for example with magnetic resonance imaging, but we will never be able to get to know the whole mind and therefore how the brain works in its entirety. It is not a question of refining the technology, because there will never be a perfect and complex technology to substitute our brains. The artificial neural networks that have been created until now, represent a real success of science, this is true, but consciousness goes beyond science itself.
To be clearer, let's take an example starting from a rather simple psychological function and of which we know, for example perception, thanks also to the Gestalt Psychology contribution more than to information theory. What we perceive, for example, when we look at an object, a painting or other, is a cognitive product that is basically based on a sensory information system, but its product goes beyond the information itself and all its possible elaborations, so it is for consciousness it can never be reduced to the functioning of the nervous substrate that creates it. Consciousness only emerges from the nervous substrate, which is another thing. As another example, think of attention, a psychological function on which many researchers have recently devoted themselves, this is a cognitive process that implies a mental process such as consciousness, it is true, but not in its subjectivity and entirety.
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John Searle. 1997. The mistery of consciousness. New York Review of Books, New York.
John Searle. 2004. Mind. A brief introduction. Oxford University Press Inc., Oxford.
Stanislas Dehaene. 2014. Consciousness and the brain. Viking Press, New York.
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Michael Graziano. 2019. Rethinking consciousness. W. W. Norton & Company, Inc., New York.
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