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Friday, June 30, 2017

Reality and Its Images

The Nature of Reality:
Realism and Idealism
Quasi-Realism
Representationalism

A few hundred years ago, a philosopher named René Descartes had a revelation. He realized that he believed many things about the way the world was, but had never thought about why. When he examined his knowledge, he found a complex web of hierarchies and feedback loops, with no clear foundation. So he decided to doubt as many things as possible, to search for the immutable foundation on which true knowledge could be built. What he discovered was revolutionary: his beliefs, his perceptions, and even his very senses might be manipulated, and for all he knew, the very world he lived in could be an illusion.

We live in a world of sight, sound, touch, taste, smell, up and down, hot and cold. These, and more, are our senses, and they work together to paint a picture of a world we accept as real. We see our hand in front of our eyes. We can reach forward and touch the desk, feeling its smooth yet grippy texture. We can walk out the door and see the sky, feel the breeze, smell the summer air. It feels so real. So present. So true.

As I walked along the sidewalk on my way home from the university one day, I was struck by the sight of a tree. It was not unusual, just one of the average variety you can find all over the Midwestern United States. It had a long, thick trunk, branches that spread out like a shelter from the sky, and a shaggy head of leaves. I reached out and touched it, feeling the roughness of the bark, and was hit full force by the fact that this tree as I saw and felt it was a creation in my mind, an image built from nerve signals feeding into my brain. Yet the tree itself has its own existence, independent from and different from the way I perceive it to be.

We unconsciously assume that the world as we see it is reality, but in fact it is not. What we perceive is our mind's picture of reality, constructed from the data our senses bring to it. To illustrate, let's talk about what it means to see something. First, light falls on the object, bouncing off it. Some of that light goes into our eyes, where it is focused onto the retinas in the backs of our eyeballs. The rod and cone cells in our retinas translate the light into electrical signals, which travel up our optic nerves into our brain. Finally, the visual cortex in our brain processes the electrical signals into the colors and shapes that we experience. From object to light to electrical signal to picture, the object and the image that we mistake for the object are four steps removed.

In order for us to perceive something, there must be a representation of it constructed in our mind. This representation is not the thing itself; it is always at least one step removed. The stunning consequence of this is that reality-in-itself cannot be known. It is logically impossible. The only exception to this is experience itself. When we see a flash of light, we can know with absolute certainty that we are seeing a flash of light, but whether it came from a real lightning bolt or the illusion of a lightning bolt is open to question. This is the metaphysical theory of representationalism.

So what is real? If we cannot experience reality-in-itself, if everything including the ideas constructed in your brain about what is written on this page are mere representations, is it possible to know anything? Can truth exist? I would say yes. Even though we can never know anything directly, that does not mean we cannot know it at all. The truth of our picture of reality is proportional to how well we can draw lines between the pieces of our picture and reality. Of course, because we cannot perceive reality directly, neither can we be absolutely sure the connecting lines between our picture and reality actually work. But it does not matter if we know it works, only if it does work. This leaves us with uncertainty, but it can be made small enough that we can justify being pragmatic about it and assuming we know what is true.

Representationalism implies something that we may never have thought of before: any organization of information, be it neural impulses, computer bits, written symbols, frozen magnetic fields, or anything else, as long as it has a systematic correlation with reality, is equally true. This idea of different but equally true ways to represent reality can show us new ways to connect with others. I never feel like I truly understand any idea or concept until I can see it as a picture in my mind's eye. One of the physics professors at my university sees the world entirely in equations. Some of the students I teach think in terms of words. Finding ways to translate between these views lends to richer, more comfortable communication with people, and I even find it to be fun.

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