Imagine you are in an isolation tank. All you can sense (barely) is the lukewarm water in which you float. You hear nothing except the slightest movements of water against the side of the tank. You see nothing. You smell nothing. And you taste nothing but your own saliva.
Now imagine that a video screen is added to your isolation tank connected to a camera outside the tank that shows you an image of the world around your tank. And a microphone is added. Then, with some cool new technologies, scents are wafted to your nostrils. You begin to get an idea of what the outside world is like from the vantage point of your isolation tank.
Now imagine that your isolation tank is mobile – it is re-engineered to be small enough that you can walk around in a roughly body-shaped tank even though you remain immersed in water. Servos help move your massive limbs, which articulate your strange machine torso and limbs. The technologists add even niftier gadgets that allow you to feel the outside world from the “skin” of your isolation tank, based on contact with the outside of the tank. And a tube is added that allows food to enter your mouth from the outside and another tube for waste. You now have almost normal access to the outside world from within your isolation tank. You could remain perhaps indefinitely in this unnatural environment.
Now imagine that this scenario is real. In fact, little imagination is required. We do exist in biological isolation tanks that we call our bodies. Literally all we know about the external world comes from various sensory “windows” we have to the external world. The world we know is entirely a creation of our brains, our nervous systems, with its various perceptual abilities. We can never know what really is the cause of our perceptions. All we know directly are our perceptions.
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