I have a map printed in Germany around 1530 that shows the world as it was seen by second century Greeks. Why would Europeans print a map that was based on sources roughly 15 centuries old? Because Europeans assumed the Greeks knew what they were doing.
Claudius Ptolemy, a Greek mathematician living in Alexandria, wrote a textbook called Geography in 150 AD. The book was so popular and reprinted so frequently – often in Arabic – that Ptolemy became known as the Father of Geography.
My map bears the heading, Le Monde Selons Ptol. or The World According to Ptolemy. It doesn’t include America even though it was printed roughly 40 years after Columbus sailed and roughly 25 years after the Waldeseemüller map became the first map ever to use the word “America”.
When my map was printed, Europe was going through an intellectual revolution. The basic question was: should we believe our traditional sources or should we believe our eyes? Should we copy Greek and Arabic sources or should we observe the world around us? Should we simply accept the Greek version of the world (as we have for so many centuries) or is “progress” something we can realistically aim for?
For centuries, Europeans assumed that the Greeks knew it all. There was no point observing the world and learning new tricks. One could live the best life by bowing to tradition, authority, and faith. This assumption held, in many quarters, until the early 16th century. Then it rapidly changed. You can see it in the maps. By 1570, most maps were in the style of tavola nuova — new maps — based on actual observations. The world had changed and, indeed, the tavolas nuovas look quite a bit like the maps we’re familiar with.
Let’s fast forward to 1900. What did we assume then? Three isms dominated our thinking: Darwinism, Marxism, and Freudianism. Further, we assumed that physics was almost finished – we had only a few final problems to work out and then physics would be complete. We assumed that we were putting the finishing touches on our knowledge of ourselves and the world around us.
But, of course, we weren’t. Today, Darwinism survives (with some enhancements) but Marxism and Freudianism have been largely cast aside. And physics is nowhere near complete. In fact, it seems that the more we learn, the more confused we become.
Even in my lifetime, our assumptions have changed dramatically. We used to believe that economics was rational. Now we understand how irrational our economic decisions are. We once assumed that the bacteria in our guts were just along for the ride. Now we believe they may fundamentally affect our behavior. We used to believe that stress caused ulcers. Now we know it’s a bacteria. Indeed, we seem to have gotten many things backwards.
And what are we assuming to be true today that will be proved wrong tomorrow? In the 16th century, we believed in eternal truths handed down for centuries. I suspect the 21st century won’t be a propitious time for eternal truths. The more we learn, the weirder it will get. Hang on to your hat. That may be all you’ll be able to hang onto.