Yuval Noah Harari is an Israeli historian who has written three best-selling books. His middle book Homo Deus raises important questions about brain and mind whose answers depend on psychology, neuroscience, and philosophy of mind.
Harari says that nobody has any idea how biochemical reactions and electric currents of the brain create the subjective experience of pain, anger, or love. This claim is challenged by a neural theory of emotions based on semantic pointers, which are representations that combine the appraisal and physiological aspects of emotions. This emotion theory meshes with the theory of consciousness that emotions and other mental states are the result of the formation of semantic pointers which then compete to be conscious. Other neural theories of emotion and consciousness have been proposed.
Pain is the simplest case. When skin is damaged, nociceptors in the skin send signals through the spinal cord to the brain, where the signals are processed in areas that include the insula and amygdala. The brain forms representations of the pain that outcompete other semantic pointers and thereby become conscious.
Harari rejects the analogy between mental states such as anger or love and other natural processes such as traffic jams and economic crises that emerge from the interactions of many parts. He claims that a traffic jam just sums up a bunch of cars slowing down, whereas anger is something completely different. But he ignores how emergent processes often produce properties that are very different from the parts of the individuals, for example when gaseous atoms of hydrogen and oxygen combine to form water which is liquid at room temperature. Similarly, when billions of neurons interact, they can have emergent properties such as consciousness that go beyond the properties of individual neurons.
Harari claims that scientists do not know what would be the evolutionary benefit of consciousness, but there are many known benefits of being conscious. First, it helps an organism to focus on what is most important for contributing to its goals by shifting from the parallel processes of neurons to the serial process of actions. Second, it aids in social interactions, because being aware of your own mental processes helps you understand what is going on in the minds of others through the process of empathy. Third, consciousness contributes to learning by teaching, in which people can figure out what they are doing by becoming consciously aware of it and thereby become more effective at passing skills to others.
Harari wonders why we need the mind if whatever happens in the mind happens in the brain. The answer is that the emergent properties of mind such as emotions and consciousness do enhance the ability of humans to survive and reproduce. Then the concept of mind has explanatory power and not does not have to join the concepts of soul, God, and immortality in the dustbin of history.
Harari claims that organisms are algorithms, but organisms are better viewed as complexes of interacting mechanisms, each of which is a combination of connected parts whose interactions produce regular changes. The mechanisms operating in your body include the digestive system, the respiratory system, the cardiovascular system, the excretory system, the reproductive system, and the nervous system. Each of these consists of organs and tissues that interact to carry out bodily functions. In contrast, an algorithm is a series of steps that accomplish a goal, for example the algorithm in your computer that enables it to multiply numbers together.
Unlike mechanisms, algorithms are abstractly characterized ignoring any particular set of parts. Multiplication algorithms can be carried out by a human, a computer, or a human using an abacus. Some mechanisms run algorithms, for example computers and brains, but other mechanisms carry out ongoing functions that do not reduce to a series of steps that are independent of the particular parts that carry them out. So algorithms and mechanisms overlap to some extent, but they are fundamentally different, and organisms are best characterized as sets of mechanisms rather than algorithms. Humans are complexes of mechanisms that include neural ones capable of operating algorithmically.
Harari is wrong that organisms are algorithms and life is data processing, because life and data processing operate with different mechanisms, except for the brain where there is some overlap. He is also wrong that intelligence is decoupling from consciousness, since in people consciousness is one of the mechanisms of intelligence, although computers are becoming increasingly intelligent without any increase in consciousness. He is mistaken that intelligent algorithms may know us better than we know ourselves because such algorithms lack introspection and empathy. His question about what is more valuable, intelligence or consciousness, is a false dilemma for people, since we have both and they interact.
In sum, Harari’s books make interesting observations and conjectures about human societies, but he needs better understanding of the operations of mind and brain.