Psychology is the study of
behaviour. To carry out their work of modifying behaviour, such as in treating
addiction, phobia, anxiety and depression, psychologists do not need to assume
people have souls. For the psychologists, it is not so much that souls do not
exist, it is that there is no need for them. It is said psychology lost its
soul in the 1930s. By this time, the discipline fully became a science, relying
on experimentation and control rather than introspection. Some of the most
notable proponents have been philosophers, such as Plato (424-348 BCE) and René
Descartes in the 17th century. Plato believed we do not learn new things but
recall things we knew before birth. For this to be so, he concluded, we must
have a soul. In the 1960s, Nobel laureate Roger Sperry showed that the mind and
our consciousness are divisible, therefore disproving that aspect of Descartes’
theory. Sperry studied patients whose corpus callosum, the superhighway
connecting the right and left hemispheres, had been severed by surgery aiming
to control the spread of epileptic seizures.
The surgery blocked or reduced
the transfer of perceptual, sensory, motor and cognitive information between
the two hemispheres. Sperry showed each hemisphere could be trained to perform
a task, but this experience was not available to the untrained hemisphere. That
is, each hemisphere could process information outside the awareness of the
other. In essence, this meant the operation produced a double consciousness. Rather than endowing rats with
souls, psychologists stripped humans of theirs. In 1949, psychologist D.O. Hebb
claimed the mind is the integration of the activity of the brain. Many
neurophilosophers have come to the same conclusion as the psychologists, with
Patricia Churchland more recently claiming there is no ghost in the machine. 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.
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