In the previous essay, we saw how philosophy embarked on a failed quest to find the core self. Something else that has occupied philosophers’ minds through the ages is the nature of reality. What is it, in and of itself? Are we in a position to know? In concepts and thought experiments like ‘the veil of Maya’, ‘Plato’s Cave’, ‘Descartes’ evil deceiver’ and ‘Nozik’s Experience Machine’, we are invited to consider the possibility that reality as perceived by the mind is an illusion, or if not an illusion then a mere shadow of a far larger reality.
KANT SEE REAL LIFE?
Immanuel Kant gave much credence to the latter possibility. He was convinced that there had to be something ‘out there’ which ultimately caused conscious experiences and sense impressions, but he argued that we knew little of what this ultimate reality was like. This was because we did not perceive a pre-given world; the structures of the mind brought forth phenomena created as much by the mind as by whatever it is that is ‘out there’.
Scientific investigations into the human body and brain seem to validate Kant’s conclusion. Consider the structure of the retina. Neurons that are sensitive to colour are found only in the middle of the retina. Beyond the middle there are neurons that can only detect light and shade. What we see, then, is a world where everything on the periphery of vision is blurry and devoid of colour, with only those objects in the centre of vision showing full colour and sharp detail. But if you study your surroundings, you will notice that this is not how you perceive the world. So, the brain must perform ‘post-processing’ in order for you to see the world as it aught to look, rather than how it does look when captured by the retina.
Another fascinating discovery is just how little information from our sense organs actually reaches the brain’s internal processing areas. Something like ten billion bits of information is picked up by the retina every second. But, there are only about a million output connections in the optic nerve, which restricts the number of bits that can leave the retina to six million. Furthermore, by the time the information is fed into the visual cortex, various bottlenecks will have reduced the number to 1000 bits, and there is still more processing to be done before the visual information gets fed into the brain regions responsible for conscious perception. How much information from the outside world constitutes conscious perception? Less than 100 bits per second.
That is far too thin a stream of data to account for the richness of conscious perception. Early brain imaging technology like PET and fMRI gave us a picture of the brain in which most neurons lay quiet until needed for some activity. Recent advances in neuroimaging, however, show that the brain is always highly active. Some 60 to 80% of all energy used by the brain occurs in circuits unrelated to any external event. This discovery, plus the fact that in the visual cortex only 10% of synapses present are devoted to incoming visual information, leads to the conclusion that there is more than a grain of truth to what Kant believed: The mind creates the world as much as it simply perceives a pre-given reality.
The view from cognitive sciences suggests that what we perceive is a fantasy that coincides with reality — at least most of the time. However,