Do you ever wonder about whether what you know is right? Most of us don’t, unless we run into something that forces us to re-evaluate things. In the heyday of the Greek philosophers, sensory input was scorned by some as being an unreliable way to learn about the world. Pure thought and the concept of meditation on the ideal form were promoted as being superior ways to know truth. As you might imagine, this kind of put a damper on scientific progress. Because if we can’t trust what we can observe, then we can’t really even do the basic type of classification that was the foundation of modern science. And if we can’t trust what we can see/hear/smell/feel/taste as being reliable guides to actual characteristics of the things in the world around us, then there is no point to setting up an experiment, which you then have to perform and collect data from, with the ultimate intent to hopefully interpret the data and figure out something new that you wanted to know. Not just something that you wanted to know, but something that was not obvious just from a casual review.
With the heights of genius that the ancient Greek philosophers reached, we moderns might wonder why it was not until approximately 2,000 years later in 1589 that Galileo performed a series of experiments using actual falling bodies to test Aristotle’s long-standing theory that heavier things fall faster than light things, in direct proportion to the weight. Aristotle taught that a 10-pound weight would fall 10 times as fast as a 1-pound weight.
Galileo’s series of experiments showed at first that light things actually fell FASTER than heavy things, before the heavy things caught up and passed the light things. But as he refined his technique (http://galileo.rice.edu/sci/theories/on_motion.html), he eventually concluded that heavy and light things fall at the same rate. The strength of the philosopher’s love affair with conceptual ideals and degradation of data collected from fallible human sensory organs is one of the main reasons for science getting such a late start compared to art, politics and other fields of human endeavor. Educated people knew that experiments with real objects were unreliable, so they were not done.
One of the other main reasons that science was held back, of course, is the more well-known mental investment in the church leaders’ interpretation of the picture of the universe that was in vogue at the time of the establishment of the Catholic church. We still live with the results of the painful science-spirit divide today. It may be shocking to some people to discover that Genesis doesn’t actually SAY anywhere that the sun circles the earth or that the earth is flat. But the post dark-age thinkers in Europe had lost a lot of the knowledge gained by observation of earlier peoples. And if the “Crown of Creation” is humans, then it follows LOGICALLY that we must be the center of the universe. Thus, the sun must circle earth.
Likewise, humans are not as perfect as the “heavens.” The “heavenly bodies” must be perfect. Aristotle was bothered by the fact that the moon was not perfectly uniform in brightness when full. It is interesting that even Leonardo da Vinci, who drew pictures of birds in flight showing the motion of individual feathers that were confirmed only in the early 1900s with high-speed zoom photography, apparently never drew an accurate picture of the moon. It seems that due to people’s beliefs that heavenly bodies are perfect and a smooth sphere is the perfect shape for a perfect body, most Europeans in the late Middle Ages were simply UNABLE TO SEE the “Man in the Moon.”
There was a revolution when people actually started using telescopes to LOOK at the moon, including Galileo, who came to the intellectually honest conclusion that the moon was not smooth. This was one argument that the church apparently did not make a big fuss over, compared to some other observational evidence... It was apparently (Aliya interpretation here) not TERRIBLY painful for the church officials to admit that the heavenly “bodies” might not all be “perfect.”
Of course we moderns are beyond all that. Even as a reasonably knowledgeable practicing engineer, it just took me about an hour and a half to gather the data (web surfing on a reasonably fast connection) to be able to report the preceding historical information to you. We have different things to worry about. The idea that experiment and observation is inherently unreliable has LONG been put to bed by scientists. We RELY most soundly (whenever possible) on a combination of theory, logically thought out, and experiment, carefully carried out. This is how we advance our knowledge today. We know that logic and reason are at least as prone to error as observation and experiment. Of course, I should not leave out the role of the hunch or inspiration as additional inputs.
Probably the most shocking technical event in my life was when I discovered that there is a form of iron oxide that has a LOWER melting point than METALLIC IRON. The first day of Materials Science 101 back in 1975 included a lecture on the general characteristics of ceramics (iron oxide), metals and polymers. One of the PRIMARY differences is that ceramics have higher melting points than metals. HOW COULD MY PROFESSORS HAVE LIED? I was shaken! Of course there are exceptions that I knew about even then. Mercury obviously is molten at temperatures where polyethylene is solid. But this was different. THIS WAS AN OXIDE OF THE SAME METAL! That day was important for me as a still relatively young practicing engineer (38 years old). I had to start to come to terms with the fact that even the things that I knew most surely might be WRONG!
The way most of us learn much of the information we use is neither by observation or logic, but by believing someone else of “greater authority.” Obviously, we are not all as smart or curious or driven as Galileo or even Aristotle. So we have to take a lot of the “knowledge” that we get for granted, at least until we are unavoidably faced with the fact that it might not be right. Today, we have available to us so much information on how our minds work and how our sensory inputs are evaluated by our minds that we would do well to spend some more time looking at the limitations of our knowledge.
With all the problems facing us, a little more intelligently applied brainpower might be helpful! A good way to start to do that is to take the time to observe some familiar objects so carefully that we see some things that we had not previously noted. I’d be interested in reports from people who try this. Your hand, a coin, a flower, a favorite trinket or piece of artwork in your home or office might be good subjects.
One of the ways that I have found to be useful in showing myself and others that we don’t see exactly what we think we see is through the use of optical illusions. You have probably seen a version of the hag and the beautiful woman (http://www.moillusions.com/2006/05/young-lady-or-old-hag.html).
Can you see the hag? Can you see the beautiful lady? In fact, most people can see both. But WE CAN ONLY SEE ONE AT A TIME. But why is this?Check in next week for the answer.
How Do You Know What You Think You Know?
By Debbie Aliya
Debbie Aliya is the owner and president of Aliya Analytical, Inc. in Grand Rapids, Mich., and specializes in failure analysis and prevention. She has a BS in Metallurgy and Materials Science from Carnegie Mellon University and an MS in Materials Science and Engineering from Northwestern University. She is also an IMT associate.