Feynman and the Philosopher

23 04 2010

Physicist Richard Feynman had a lot of things to say about philosophers. In Six Easy Pieces, he said “Philosophers say a great deal about what is absolutely necessary for science, and it is always, so far as one can see, rather naive, and probably wrong.”  A few months ago I came across a video of a lecture he gave at the University of Auckland in 1979 and he was had an entertaining answer to a question a vision scientist might spend a great deal of time thinking about.

“The question of whether or not when you see something, you see only the light or you see the thing you’re looking at, is one of those dopey philosophical things that an ordinary person has no difficulty with. Even the most profound philosopher, sitting eating his dinner, has many difficulties making out that what he looks at perhaps might only be the light from the steak but it still implies the existence of the steak which he is able to lift by the fork to his mouth. The philosophers that were unable to make that analysis and that idea have fallen by the wayside from hunger.”

Is it really relevant if we see the light of the object or the object itself? In reality, we don’t see either. We see a mental construction of the object by way of the light reflecting (or emitting) from an object. Philosophers call this a relational sense. Or mind can construct objects that don’t really exist, which philosophers call the phenomenal sense. A good example of both of these concepts is the optical illusion known as the Kanizsa triangle.

Credit: Wikipedia.org

In the figure above, there appears to be a brighter white triangle in the center, when in fact none is drawn. If you use a photometer or some type of RGB value reader for the image, you will find that the center of the image is the same brightness as the area around. Your mind constructs the triangle in the phenomenal sense. The blotches of dark pixels exist in the relational sense. This, to me, seems more of a philosophical quandary than if you see the object or the light from the object.

This is not a blog.

19 11 2009
The Treachery of Images -  René Magritte (Credit: Wikipedia.org)

The Treachery of Images - René Magritte (Credit: Wikipedia.org)

I remember one day sitting in ninth grade English class when we were having a discussion on symbolism in literature. Our teacher stood at the chalk board and asked us to list things that were symbolic to us. Listed off were such things as a broken mirror or a wedding ring when I offered the number three.

To this the teacher paused for a moment and then said, “Well, yes. The Holy Trinity is represented by the number three,” and she drew a large ‘3’ on the board.

“No, the number three is a symbolic reference for the abstract idea of three,” I stated.

My teacher and classmates were confused by this. To them, rain clouds and black cats were symbols because they were something a person would use to mean something else, but the number three was a concrete concept, when in fact it represents one of the highest forms of abstract thought man has. But if you had told me at that time that everything we see is symbolic, I would have had as much trouble believing that as my classmates did that three is symbolic. But it is the truth, we don’t see the world, we see a symbolic representation of the world!

How exciting is that concept! I will understand if you have some difficulty coming to terms with this idea. Here is an example to help illustrate this fact:

The Necker Cube (Credit: BenFrantzDale, Wikipedia.org)

The Necker Cube (Credit: BenFrantzDale, Wikipedia.org)

This image is called the Necker Cube, after it’s creator, Louis Albert Necker. Most people know this illusion: you stare at the image and a 3D cube appears, and then after a bit a different cube appears. This brings up the question, where is the other cube when the new one appears? This requires a bit of thought. If you were to touch your computer monitor, you would feel a smooth flat surface, not the sharp edges that you see on the cube. That gives us two options:

  1. There is a disconnect between our sense of vision and our sense of touch. The object is a cube, but our sense of touch is in error.
  2. That our mind actively constructs the cube.

Option 2 is the easier one for me to accept, and we have further evidence that it is correct because we switch between two versions of the cube as our mind switches constructions. Our minds construct a symbolic interpretation of a cube.

We can also look at what our minds fail to construct. Here is an optical illusion known as the lilac chaser. If you stare at the center cross for about 20 seconds, something rather amazing happens.

Source: Jeremy Hinton; Wikipedia.org

As you could see, the grey space between the dots appears to become a green dot, and then suddenly the green dot gobbles up the lilac dots as it goes around the circle.

These two cases bring up an important point, that we construct the reality that we see. In one case, we constructed two boxes where in actuality none existed, in the other, we removed what was actually there. You might think that these are rather extreme or limited cases, but actually construction takes place actively all the time.  Take a look at these two videos, which describe the “hollow face mask” illusion.

What you see in the hallow face mask illusion is the brain actively constructing a view of reality based on what it expects to see. My favorite filmmaker, Errol Morris, once said “Reality is reenacted inside our skulls routinely. That’s how we know about the world. We walk around in the world, the world isn’t walking around in us.”

This brings me back to the painting I included at the beginning of this essay, René Magritte’s The Treachery of Images.

The Treachery of Images - René Magritte (Credit: Wikipedia.org)

The caption to this painting translates to “This is not a pipe.” Magritte commented on this caption by saying, “”The famous pipe. How people reproached me for it! And yet, could you stuff my pipe? No, it’s just a representation, is it not? So if I had written on my picture ‘This is a pipe,’ I’d have been lying!” That’s something I really want to convey through this blog: that images are our way of interfacing with reality. It’s by no means correct, complete, or accurate, but it’s what we have. And the more we understand the process, the more we will not only understand about ourselves, but also the world around us.

Getting things ready…

14 10 2009

Welcome! Go Away! We’re not ready!

In the meantime please enjoy this comic from xkcd.


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