Avicenna was an Arabic philosopher who lived from 980 to 1037. He followed the Greek wisdom, consciously rejecting Islamic theology. He wrote in “On The Soul” the following thought experiment:
- If I were blindfolded and suspended in the air, touching nothing …
- I would not know that I have a body.
- But I would know that I – my “self” or “soul” exists.
- So, my soul is not a body, but something different.
- The soul is distinct from the body.
Suppose you are in absolute empty space. There would be no light, sound, smell, taste, sense touch. Suppose there are no sensations, would you know what you areor where you are? The jump from Proposition 2 to Proposition 3 is a large one that cannot be proven.
Suppose that it is true, then one must ask, “what is the body for,” if the self or soul can survive in such a state. It also begs the question does that mean there is a place as absolute empty space, where such a soul can exist?
Of course, Avicenna did not have the benefit of knowledge that we have today of human physiology. We know the brain gives us the sense of self.
Let’s modify the experiment and take two people.
One is born with everything to be a human, except for the input of sensation. Would he or she know of his or her existence? The perceptual brain would be running but with no information of the world or self.
Another person came into the world the same way, had one day of sensation before all senses were taken away. Would he or she know of his or her existence. Now, at least this person has had some input. This input is processed by the brain, trying to make sense of the experience. From the available information the brain would try to sense of the world, perhaps seek out more information from the senses, try to turn it back on.
To know the self requires that we know the existence of the “other”, some thing of the external world.
Coma patients are a bit like the second person. They are temporarily (or until death) not aware of the “outside” world, even though they are alive and function as long the body is nourished and the brain is undamaged. This shows clearly we only have access to the outside world though the senses. While this coma patient has no more sensory input he or she still has perceptual and conceptual input. Thoughts may continue because there is “something there” to think about. Unlike the first person in the thought experiment there is no seed of information to start perception and conception.
Perception and conception can only start when some input is given. That input, it seems, is from sensation or sense data.