Critical Thinking

by Norm Nason

When I was in the sixth grade (longer ago than I care to admit), the elementary school I attended administered a program that has benefited me ever since. Not long before graduating, a single week was set aside to prepare departing students for their move up the ladder of higher education. For five days we no longer attended a single classroom, but rather six, as would later be the case in Junior High, High School and College. Separate teachers instructed us on a variety of topics: Music, History, Art, Science, Literature, and, my favorite—Critical Thinking. This class was taught by Mr. Anderson, a teacher unfamiliar to me at the time.

Although the specifics of Mr. Anderson's instruction escape me, the essence of it was this: Think about what you are saying and doing. When observing the world, make critical, logical deductions. Try to figure things out for yourself, rather than believing everything you hear out of hand. Insist upon getting the facts, and learn to recognize them; find proof. Say precisely what you mean; do exactly what you resolve. Demonstrate conviction in your thoughts and actions. Be decisive. Use your noodle!

Amazing stuff, coming from an elementary school teacher; don't you agree?

Throughout my life I have often thought about what Mr. Anderson said, and have tried my best to apply it. I've observed that many of man's false beliefs could have been avoided if only the majority practiced critical thinking. Take, for example, the once widely held belief that the Earth was flat. A critical thinker might look up into the sky, see the sun and moon, and from this deduce that the Earth was not flat at all, but round. Why? The moon and sun are round; perhaps it is more logical to conclude that the Earth is similar, rather than different. True, you might say, but how do we know they are not simply flat disks, like coins, rather than spheres? The answer: when we observe the phases of the moon, a shadow moves nightly across its face, having specific visual characteristics. When we try to duplicate these characteristics experimentally, we find that the only way they may be replicated are on the surface of a sphere. All right, you might admit, the Earth could be round, but how shall we prove it? Perhaps in the manner that the young Columbus is reported to have done: by observing the masts of departing sailing vessels sinking ever lower on the horizon. Or, we might do as a Greek philosopher did around 250 B.C.:

Eratosthenes was told that on a certain day during the summer (June 21) in a town called Syene, which was 4900 stadia (1 stadia = 0.16 kilometers) to the south of Alexandria, the sunlight shown directly down the well shafts so that you could see all the way to the bottom. Eratosthenes knew that the sun was never quite high enough in the sky to see the bottom of wells in Alexandria and he was able to calculate that in fact it was about 7 degrees too low. Knowing that the sun was 7 degrees lower at its highpoint in Alexandria than in Syene and assuming that the sun's rays were parallel when they hit the Earth, Eratosthenes was able to calculate the circumference of the Earth using a simple proportion: C/4900 stadia = 360 degrees/ 7 degrees. This gives an answer of 252,000 stadia or 40,320 km, which is very close to today's measurements of 40,030 km.

You get the idea. Critical thinking has solved many of the world's mysteries—perhaps most—and is the spearhead of human progress. Continental drift, implied by a map of the world; a case for mass extinctions (and even human evolution), deduced from observing the craters of the moon; clues coming to light about brain function by noting the time lag between reaction to stimulus and conscious awareness...all are examples of critical thinking at work.

Mr. Anderson, wherever you are, I thank you.