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We were talking in class on Thursday about the fact that the human system for vision is not perfect, just a system that happens to work most of the time.  It’s strange to think that vision is more likely to not work well than to work well, but it does go a long way towards explaining why so many people need glasses, and most people end up needing them as they age. It reminded me of the argument for intelligent design, that something as complicated as the human eye could not have evolved without the influence of a creator. The fact that the human eye doesn’t work perfectly is good evidence for the fact that it is a product of evolution. Evolution simply favors what works, even if it isn't perfect. A "designer" wouldn't likely have created something that doesn't work perfectly, and certainly wouldn't have created something that doesn't work well much of the time.

The idea that an unconscious part of the nervous system fills in the gaps in your vision, along with the fact that even if you know about the gaps in your vision you can never actually see them, raises some interesting questions. To what degree does unconscious mind control behavior? How much of our unconscious behavior can we change if we become consciously aware of it? It’s also strange to think much of the information that is transmitted to our eyes is thrown away before it reaches the nervous system, and it just fills in the gaps. How much of the time is what our nervous system fills in different from what is actually there?