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What is the Mind-Body problem?
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Hemiplegic stroke victims

In a case study, hemiplegic stroke victims perceived themselves as fully able-bodied. Even though they were paralyzed, they claimed they could move both sides of their body, thus presenting the possibility that one’s experience of the world only exists in the mind.


Idealists believe that only the mind exists and everything that we perceive in the physical world is merely a composition [1]. There are many positions under the idealism umbrella, including phenomenalism and subjective idealism- which asserts that the mind is the only thing that really exists. Bishop Berkeley, or George Berkeley, was a prominent Irish idealist from the 17th and 18th centuries. He promoted the idea that our bodies are nothing more than a perception of the mind.[2] Immanuel Kant also considered himself a transcendental idealist or a critical idealist. His metaphysical theory supposed that space and time did not exist outside of the mind and were instead our own perceptions.[3]

The Argument

In a 1996 study, scientists conducted an experiment on three hemiplegic stroke victims. Each victim was totally paralysed on one side of the body due to damage to the right hemisphere of the brain, in each case, this was caused by a stroke. When asked, all three victims claimed their right and left arms were equally mobile. Despite visual evidence to the contrary, the victims felt as though their right side was not paralysed but was moving unimpeded and unhindered when prompted. This perception of the body which does not align with outsider’s perceptions could indicate that our body is simply an extension of our mind and is simply a projection of what we perceive our body may look like.

Counter arguments

Experience A famous interaction between Swift and Berkeley best demonstrates one of the main challenges to idealist thought. Swift allegedly left Berkeley standing outside his door in the pouring rain one day to demonstrate the holes in his theory. Swift’s reasoning was that if Berkeley’s argument rang true, he would be just as able to enter the building with the door closed as he would with it open. His body would not exist beyond the non-physical realm. Nor would the door. It is all in his non-physical mind. Therefore, nothing would stop him walking through the door.[4] The experience of daily life stands in direct contrast to idealism. Every interaction that takes place between our body and the external world stands in direct contrast to idealist belief. Idealists must doubt the very evidence our senses present to us. Dreams and Memory When we dream, imagine fictitious scenarios and think back about past events, we are aware that what is being played out in our minds is not present in reality. At no point do we become so lost in our memories that we forget that it is not taking place in the present. Dreams and memories appear to refute the idealist position. If, as idealists argue, everything we perceive only exists in the mind, then how would we be able to move seamlessly between dreams and real life? There would be no waking moment where we ceased existing in the mental realm and began experiencing the physical one. There would be no means of knowing where the dream ended, and life began. The same applies to memory. I can recall in my mind a tree that I saw yesterday. However, it is clear to me that now I am remembering, while yesterday I was experiencing. There is a clear distinction between experiencing the present and remembering the past. If both were the same- nothing more than mental, non-physical experiences, I would have a much more difficult time differentiating between the two.



Only the mind exists. Our perception of the world is only a perception of our minds.

Rejecting the premises

We cannot break the laws of physics with our mind. Therefore, there must be a physical world that exists outside of our minds.


This page was last edited on Tuesday, 9 Jun 2020 at 03:06 UTC