Tuesday, May 28, 2013

Thales of Miletus, Philosopher

All things come from water.

First, some epistemological questions!  It's natural to assume that you know everything, and that your knowledge is secure because, well, you just know it.  But consider:
  • Is it possible to have knowledge at all?
  • Can our reason provide us with knowledge of things that we cannot experience? 
  • Does our knowledge present reality as it really is?
Now that we've thought about those questions for a moment, let's move on to a look at this guy Thales.

The philosopher A. N. Whitehead famously said that all of western philosophy is just a "series of footnotes to Plato."  While he has a point, his quote suggests that Plato was the first thinker that  mattered.  Doing so would be a great disservice to this man, Thales, who was the first person we can legitimately call a "philosopher." And I've chosen to write about him today, on May 28, for a reason you will see in a moment.

Almost everything we know about the pres-Socratic philosopher Thales (and that's pronounce Tah-les, please) is conjecture.  It's impossible to say anything about him with conviction, and everything we know about him is shrouded in uncertainty. 

But let's examine the probable.  He was probably born in Miletus, present day Turkey, around 624 BCE.  He was naturally interested in astronomy and the physical world, and, according to one story, he was walking with his gaze at the stars instead of in front of him when he fell into a well.  According to another story, a critic mocked him for his lack of wealth, unable to understand how one could be both wise and poor.  

Thales cured that poverty one year, allegedly, when he realized that the Mediterranean was about to enjoy a bumper crop of olives.  He bought all of the olive presses in Miletus, and then waited until the olives came running in.  When the famers were clamoring for use of the press, he rented them out at exorbitant rates, made a fortune, and then sold the presses when the season was over.

He may have invented deductive mathematics, which you are familiar with if you have ever had to do a proof in high school geometry.  He reasoned that vertically opposite angles are equal, and discovered that a circle is bisected by its diameter.  

If you are not impressed yet, wait till you hear how he calculated the height of the pyramids.  Thales was the first to understand that triangles with like angles were alike in all ways, and he (probably) used this understanding to determine the height of the pyramids.  At that time, nobody knew how tall they were.  But Thales knew the dimensions of the pyramid's footprint (252 paces square), and used this knowledge to learn the unknown height of the structure.  He measured how long the shadow was from the center of the pyramid to the tip of its shadow.  Then he measured the length of his own shadow and compared it to his height and came up with a ratio.  He compared the two ratios, and was able to come up with his answer: the pyramid at Giza was 160 paces tall.

By using what he knew (the dimensions of the pyramid's footprint and his own height), he found an unknown (the height of the pyramid.) To borrow a word from Archimedes: eureka.
The triangles formed by the ground, the standing figure, and the shadow are all right triangles, and, consequently, share the same properties.  
But all of this math business is just prologue to my favorite of Thales accomplishments.  He seems to have deduced that all things in the world spring from a common "original principle," and that this principle is water.  To put it more clearly, I like to believe that Thales came up with this simple declarative statement:

"All things come from water."

For the first time in western history, a thinker had imagined that the world worked on rational principles--that all things started from one place and had an understandable reason for being.  His answer to the question "Where do things come from?" was not Zeus, nor God, nor magic, but water.

So, why did I choose to create this post on May 28?  Well, according to another story, this one from Thucydides,  Thales was the first person to predict a solar eclipse.  The date was May 28, 585 BCE. That day fell during the Battle of Halys, between the Medes and the Lydians, and when the sun disappeared just as Thales had predicted, the warring sides spontaneously stopped fighting and signed a truce.

Furthermore, this date, May 28, 585 BCE, became a benchmark date that future historians used to determine the dates of many different events.  Just as Thales was able to determine the height of the pyramid once he had a known value, historians have been able to use this known date to figure out many unknowns.

Is it true?  Did it really happen?  Is it reality?  Can we say this happened even though we were not there to see it?  Well, who knows?

Works Cited:

"Thales." World of Scientific Discovery. Gale, 2006. Student Resources in Context. Web. 27 May 2013.
"Thales (c. 624 B.C.-c. 545 B.C.)." Encyclopedia of World Biography. Detroit: Gale, 1998. Gale     
      Power Search. Web.

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