The brain does it all
If the soul is where emotion and motivation reside, where mental activity occurs, sensations are perceived, memories are stored, reasoning takes place and decisions are taken, then there is no need to hypothesise its existence. There is an organ that already performs these functions: the brain.
This idea goes back to the ancient physician Hippocrates (460-377 BCE) who said:
Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency and lamentations. And by this … we acquire wisdom and knowledge, and see and hear, and know what are foul and what are fair, what are bad and what are good, what are sweet and what are unsavoury…
The brain is the organ with a map of our body, the outside world and our experience. Damage to the brain, as in accidents, dementias or congenital malformations, produces a commensurate damage to personality.
Consider one of the functions supposedly – if we listen to Plato – carried out by the soul: memory. A major knock on the head can make you lose your memories of the past several years. If the soul is an immaterial substance separate from our physical being, it should not be injured by the knock. If memory were stored in the soul, it should not have been lost.
The neuronal activity in the brain is responsible for the cognitive and emotional dysfunctions in people with autism; it would be cruel and unethical to blame their hypothetical souls.
Manipulation of the brain is sufficient to alter emotion and mood. The soul is totally superfluous to this process.
The ability of psychotherapeutic drugs to alter mood provides another line of evidence against the presence of the soul. If you produce a chemical imbalance in the brain, such as by depleting dopamine, noradrenaline and serotonin with tetrabenazine, you can induce depression in some people.
Correspondingly, many depressed people can be helped by drugs that increase the function of these neurotransmitters in the brain.
The brain is where thinking takes place, love and hatred reside, sensations become perceptions, personality is formed, memories and beliefs are held, and where decisions are made. As D.K. Johnson said: “There is nothing left for the soul to do.”
George Paxinos, Visiting/Conjoint Professor of Psychology and Medical Sciences, UNSW & NHMRC Australia Fellow, Neuroscience Research Australia
This article was originally published on The Conversation.
George Paxinos, Neuroscience Research Australia